Re: malloc() call somehow calling the rtld malloc() implementaion

[Don Lewis]

On 27 Jan, Alexander Kabaev wrote:
> On Fri, 27 Jan 2017 10:47:20 -0800 (PST)
> Don Lewis  wrote:
> 
>> On 27 Jan, Alexander Kabaev wrote:
>> > On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
>> > Don Lewis  wrote:  
>> 
>> >> If I create a simple test program that calls malloc() and set a
>> >> breakpoint in malloc(), the breakpoint gets set in the rtld
>> >> version, but the the libc version of malloc is what gets called.
>> >> 
>> >> What the heck is going on here, and how can I fix it?
>> >>   
>> > 
>> > rtld on my system does not have malloc exposed as dynamic symbol, it
>> > cannot possibly be used for symbol resolution by any outside
>> > module.  
>> 
>> Same here, but gdb at least seems to find it anyway.
>> 
>> 12.0-CURRENT r311765M
>> 
>> %nm /libexec/ld-elf.so.1
>> nm: /libexec/ld-elf.so.1: no symbols
>> 
>> %elfdump -s /libexec/ld-elf.so.1 | grep st_name | sort
>>  st_name: 
>>  st_name: 
>>  st_name: FBSD_1.0
>>  st_name: FBSD_1.1
>>  st_name: FBSD_1.2
>>  st_name: FBSD_1.3
>>  st_name: FBSD_1.4
>>  st_name: FBSD_1.5
>>  st_name: FBSDprivate_1.0
>>  st_name: __tls_get_addr
>>  st_name: _r_debug_postinit
>>  st_name: _rtld_addr_phdr
>>  st_name: _rtld_allocate_tls
>>  st_name: _rtld_atfork_post
>>  st_name: _rtld_atfork_pre
>>  st_name: _rtld_error
>>  st_name: _rtld_free_tls
>>  st_name: _rtld_get_stack_prot
>>  st_name: _rtld_is_dlopened
>>  st_name: _rtld_thread_init
>>  st_name: dl_iterate_phdr
>>  st_name: dladdr
>>  st_name: dlclose
>>  st_name: dlerror
>>  st_name: dlfunc
>>  st_name: dlinfo
>>  st_name: dllockinit
>>  st_name: dlopen
>>  st_name: dlsym
>>  st_name: dlvsym
>>  st_name: fdlopen
>>  st_name: r_debug_state
>> 
>> %cd /tmp
>> zipper:/tmp 508%cat malloctest.c 
>> #include 
>> volatile void *p;
>> int
>> main(void) {
>>  p = malloc(16);
>> }
>> %cc -g malloctest.c
>> %gdb a.out
>> GNU gdb 6.1.1 [FreeBSD]
>> Copyright 2004 Free Software Foundation, Inc.
>> GDB is free software, covered by the GNU General Public License, and
>> you are welcome to change it and/or distribute copies of it under
>> certain conditions. Type "show copying" to see the conditions.
>> There is absolutely no warranty for GDB.  Type "show warranty" for
>> details. This GDB was configured as "amd64-marcel-freebsd"...
>> (gdb) break main
>> Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
>> (gdb) run
>> Starting program: /tmp/a.out 
>> 
>> Breakpoint 1, main () at malloctest.c:5
>> 5p = malloc(16);
>> Current language:  auto; currently minimal
>> (gdb) break malloc
>> Breakpoint 2 at 0x80060e9a4: file /usr/src/libexec/rtld-elf/malloc.c,
>> line 163. (gdb) cont
>> Continuing.
>> 
>> Program exited normally.
>> (gdb) quit
>> 
>> Ports gdb finds both the rtld malloc() and the libc malloc():
>> 
>> %/usr/local/bin/gdb a.out
>> GNU gdb (GDB) 7.12 [GDB v7.12 for FreeBSD]
>> Copyright (C) 2016 Free Software Foundation, Inc.
>> License GPLv3+: GNU GPL version 3 or later
>>  This is free software: you are
>> free to change and redistribute it. There is NO WARRANTY, to the
>> extent permitted by law.  Type "show copying" and "show warranty" for
>> details. This GDB was configured as "x86_64-portbld-freebsd12.0".
>> Type "show configuration" for configuration details.
>> For bug reporting instructions, please see:
>> .
>> Find the GDB manual and other documentation resources online at:
>> .
>> For help, type "help".
>> Type "apropos word" to search for commands related to "word"...
>> Reading symbols from a.out...done.
>> (gdb) break main
>> Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
>> (gdb) run
>> Starting program: /tmp/a.out 
>> 
>> Breakpoint 1, main () at malloctest.c:5
>> 5p = malloc(16);
>> (gdb) break malloc
>> Breakpoint 2 at 0x80060e9a4: malloc. (2 locations)
>> (gdb) cont
>> Continuing.
>> 
>> Breakpoint 2, __malloc (size=16) at jemalloc_jemalloc.c:1636
>> 1636 size_t usize JEMALLOC_CC_SILENCE_INIT(0);
> 
> gdb looks into debugging info for symbols in debug information and so
> has greater visibility. Symbols gdb sees play no role in dynasmic
> building, so rtld malloc somehow replacing the malloc from the program
> as you suspected is really impossible.

What threw me off here was that ld-elf.so is stripped, so I didn't think
that it had debug symbols available.  I'd forgotten that we now install
.debug files for the base system executables and shared libraries.

> kib@ has a better idea that is worth investigating further: is the
> address on which idlc traps corresponds to TLS storage? tls alloc calls
> are supposed to respect the tls section alignment though.

Once I had ports gdb available in the jail so that I could set
breakpoints in both versions of malloc(), I was able to see that all of
the rtld malloc() cal

Re: malloc() call somehow calling the rtld malloc() implementaion

[Don Lewis]

On 27 Jan, Konstantin Belousov wrote:
> On Fri, Jan 27, 2017 at 12:19:16PM -0500, Alexander Kabaev wrote:
>> On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
>> Don Lewis  wrote:

>> > If I create a simple test program that calls malloc() and set a
>> > breakpoint in malloc(), the breakpoint gets set in the rtld version,
>> > but the the libc version of malloc is what gets called.
>> > 
>> > What the heck is going on here, and how can I fix it?
>> > 
>> 
>> rtld on my system does not have malloc exposed as dynamic symbol, it
>> cannot possibly be used for symbol resolution by any outside module.
> 
> Sure.
> 
> Also, the fact that rtld internal malloc is called does not mean that it
> is called by the application. There is no backtrace which would describe
> the reason for rtld allocating memory in reported cases. Generally,
> rtld needs memory for TLS allocation (the program is definitely linked
> with libthr, and even libc uses TLS), and, of course, to create data
> structures to track dlopen-ed objects.

After adding ports gdb as a RUN_DEPENDS so that it gets installed in the
poudriere jail that I was using for debugging, I can confirm that this
is exactly what is happening.  All of the calls to the rtld version of
malloc() happened before main() was entered.  Starting slightly before
the start of main() and continuing until the eventual SIGBUS, all of the
malloc() calls were to the version in libc.


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Re: malloc() call somehow calling the rtld malloc() implementaion

[Don Lewis]

On 28 Jan, Jan Mikkelsen wrote:
> Hi,
> 
> Are you being affected by this rtld behaviour:
> 
> https://lists.freebsd.org/pipermail/freebsd-hackers/2016-July/049769.html 
> 
> 
> https://lists.freebsd.org/pipermail/freebsd-stable/2015-July/082751.html 
> 
> 
> (I still find this a bit scary.)

That's not rtld, it's the kernel linker.  Yes, I have also encountered
that, though in my case the effect was that it hid the fact that the
target symbol was not exported.  There was a linking failure on i386,
which the amd64-only testing did not uncover.

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Re: malloc() call somehow calling the rtld malloc() implementaion

[Don Lewis]

On 27 Jan, Konstantin Belousov wrote:
> On Fri, Jan 27, 2017 at 12:19:16PM -0500, Alexander Kabaev wrote:
>> On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
>> Don Lewis  wrote:
>> 
>> > I've been attempting to get OpenOffice to build properly in a
>> > clang400-import poudriere jail and have run into a mystery.  The build
>> > procedure creates a c++ executable "idlc", which is used to build
>> > other stuff.  The new operator has been overrriden to call a custom
>> > memory allocator, which I have configured to call the system version
>> > of malloc().
>> > 
>> > At some point idlc crashes because it has allocated a 16 byte
>> > structure and the compiler is using "movaps %xmm0,(%rax)" to
>> > initialize it, which requires 16 byte alignment.  Unfortunately this
>> > structure is only 8 byte aligned, causing a bus error.  This
>> > shouldn't be happening because our system malloc() always seems to do
>> > the proper alignment.  It appears that intead of calling the version
>> > of malloc() in libc, the simple version of malloc() built into rtld
>> > is being called instead.
>> > 
>> > GNU gdb 6.1.1 [FreeBSD]
>> > Copyright 2004 Free Software Foundation, Inc.
>> > GDB is free software, covered by the GNU General Public License, and
>> > you are welcome to change it and/or distribute copies of it under
>> > certain conditions. Type "show copying" to see the conditions.
>> > There is absolutely no warranty for GDB.  Type "show warranty" for
>> > details. This GDB was configured as "amd64-marcel-freebsd"...
>> > (gdb) break main
>> > Breakpoint 1 at 0x43b1f6: file idlcmain.cxx, line 34.
>> > (gdb) run @/tmp/r
>> > Starting
>> > program: 
>> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc
>> > @/tmp/r [New LWP 101304] [New Thread 802616000 (LWP 101304/idlc)]
>> > [Switching to Thread 802616000 (LWP 101304/idlc)]
>> > 
>> > Breakpoint 1, main (argc=2, argv=0x7fffb278) at idlcmain.cxx:34
>> > 34 SAL_IMPLEMENT_MAIN_WITH_ARGS(argc, argv)
>> > (gdb) break malloc
>> > Breakpoint 2 at 0x8006a5f01:
>> > file /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c,
>> > line 163. (gdb) cont Continuing.
>> > Trace 12474/1: "Min Prioriy for policy '2' == '0'
>> > "
>> > Trace 12474/1: "Max Prioriy for policy '2' == '103'
>> > "
>> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc:
>> > compiling 1 source files ...
>> > Compiling: 
>> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/offapi/com/sun/star/i18n/KParseTokens.idl
>> > 
>> > Breakpoint 2, malloc (nbytes=343)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:
>> > No such file or directory.
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > Current language:  auto; currently minimal (gdb) cont
>> > Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=32)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > Trace 13112/2: "ChildStatusProc : starting
>> > '/wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/ucpp'"
>> >  [New
>> > Thread 802616500 (LWP 100249/idlc)] [Switching to Thread 802616500
>> > (LWP 100249/idlc)]
>> > 
>> > Breakpoint 2, malloc (nbytes=19)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=34)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=16)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=16)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=16)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> > 
>> > Breakpoint 2, malloc (nbytes=16)
>> > at 
>> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
>> > 163
>> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
>> > (gdb) cont Continuing.
>> >

Re: malloc() call somehow calling the rtld malloc() implementaion

[Jan Mikkelsen]

Hi,

Are you being affected by this rtld behaviour:

https://lists.freebsd.org/pipermail/freebsd-hackers/2016-July/049769.html 


https://lists.freebsd.org/pipermail/freebsd-stable/2015-July/082751.html 


(I still find this a bit scary.)

Regards,

Jan.


> On 27 Jan 2017, at 19:31, Don Lewis  wrote:
> 
> I've been attempting to get OpenOffice to build properly in a
> clang400-import poudriere jail and have run into a mystery.  The build
> procedure creates a c++ executable "idlc", which is used to build other
> stuff.  The new operator has been overrriden to call a custom memory
> allocator, which I have configured to call the system version of
> malloc().
> 
> At some point idlc crashes because it has allocated a 16 byte structure
> and the compiler is using "movaps %xmm0,(%rax)" to initialize it, which
> requires 16 byte alignment.  Unfortunately this structure is only 8 byte
> aligned, causing a bus error.  This shouldn't be happening because our
> system malloc() always seems to do the proper alignment.  It appears
> that intead of calling the version of malloc() in libc, the simple
> version of malloc() built into rtld is being called instead.
> 
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "amd64-marcel-freebsd"...
> (gdb) break main
> Breakpoint 1 at 0x43b1f6: file idlcmain.cxx, line 34.
> (gdb) run @/tmp/r
> Starting program: 
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc
>  @/tmp/r
> [New LWP 101304]
> [New Thread 802616000 (LWP 101304/idlc)]
> [Switching to Thread 802616000 (LWP 101304/idlc)]
> 
> Breakpoint 1, main (argc=2, argv=0x7fffb278) at idlcmain.cxx:34
> 34SAL_IMPLEMENT_MAIN_WITH_ARGS(argc, argv)
> (gdb) break malloc
> Breakpoint 2 at 0x8006a5f01: file 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c, line 
> 163.
> (gdb) cont
> Continuing.
> Trace 12474/1: "Min Prioriy for policy '2' == '0'
> "
> Trace 12474/1: "Max Prioriy for policy '2' == '103'
> "
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc:
>  compiling 1 source files ... 
> Compiling: 
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/offapi/com/sun/star/i18n/KParseTokens.idl
> 
> Breakpoint 2, malloc (nbytes=343)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c: 
> No such file or directory.
>   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> Current language:  auto; currently minimal
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=32)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> Trace 13112/2: "ChildStatusProc : starting 
> '/wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/ucpp'"
> [New Thread 802616500 (LWP 100249/idlc)]
> [Switching to Thread 802616500 (LWP 100249/idlc)]
> 
> Breakpoint 2, malloc (nbytes=19)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=34)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
>at /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont
> Continuing.
> sizeof(AstExprValue)=16
> 
> Program received signal SIGBUS

Re: malloc() call somehow calling the rtld malloc() implementaion

[Alexander Kabaev]

On Fri, 27 Jan 2017 10:47:20 -0800 (PST)
Don Lewis  wrote:

> On 27 Jan, Alexander Kabaev wrote:
> > On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
> > Don Lewis  wrote:  
> 
> >> If I create a simple test program that calls malloc() and set a
> >> breakpoint in malloc(), the breakpoint gets set in the rtld
> >> version, but the the libc version of malloc is what gets called.
> >> 
> >> What the heck is going on here, and how can I fix it?
> >>   
> > 
> > rtld on my system does not have malloc exposed as dynamic symbol, it
> > cannot possibly be used for symbol resolution by any outside
> > module.  
> 
> Same here, but gdb at least seems to find it anyway.
> 
> 12.0-CURRENT r311765M
> 
> %nm /libexec/ld-elf.so.1
> nm: /libexec/ld-elf.so.1: no symbols
> 
> %elfdump -s /libexec/ld-elf.so.1 | grep st_name | sort
>   st_name: 
>   st_name: 
>   st_name: FBSD_1.0
>   st_name: FBSD_1.1
>   st_name: FBSD_1.2
>   st_name: FBSD_1.3
>   st_name: FBSD_1.4
>   st_name: FBSD_1.5
>   st_name: FBSDprivate_1.0
>   st_name: __tls_get_addr
>   st_name: _r_debug_postinit
>   st_name: _rtld_addr_phdr
>   st_name: _rtld_allocate_tls
>   st_name: _rtld_atfork_post
>   st_name: _rtld_atfork_pre
>   st_name: _rtld_error
>   st_name: _rtld_free_tls
>   st_name: _rtld_get_stack_prot
>   st_name: _rtld_is_dlopened
>   st_name: _rtld_thread_init
>   st_name: dl_iterate_phdr
>   st_name: dladdr
>   st_name: dlclose
>   st_name: dlerror
>   st_name: dlfunc
>   st_name: dlinfo
>   st_name: dllockinit
>   st_name: dlopen
>   st_name: dlsym
>   st_name: dlvsym
>   st_name: fdlopen
>   st_name: r_debug_state
> 
> %cd /tmp
> zipper:/tmp 508%cat malloctest.c 
> #include 
> volatile void *p;
> int
> main(void) {
>   p = malloc(16);
> }
> %cc -g malloctest.c
> %gdb a.out
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and
> you are welcome to change it and/or distribute copies of it under
> certain conditions. Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details. This GDB was configured as "amd64-marcel-freebsd"...
> (gdb) break main
> Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
> (gdb) run
> Starting program: /tmp/a.out 
> 
> Breakpoint 1, main () at malloctest.c:5
> 5 p = malloc(16);
> Current language:  auto; currently minimal
> (gdb) break malloc
> Breakpoint 2 at 0x80060e9a4: file /usr/src/libexec/rtld-elf/malloc.c,
> line 163. (gdb) cont
> Continuing.
> 
> Program exited normally.
> (gdb) quit
> 
> Ports gdb finds both the rtld malloc() and the libc malloc():
> 
> %/usr/local/bin/gdb a.out
> GNU gdb (GDB) 7.12 [GDB v7.12 for FreeBSD]
> Copyright (C) 2016 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
>  This is free software: you are
> free to change and redistribute it. There is NO WARRANTY, to the
> extent permitted by law.  Type "show copying" and "show warranty" for
> details. This GDB was configured as "x86_64-portbld-freebsd12.0".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> .
> Find the GDB manual and other documentation resources online at:
> .
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from a.out...done.
> (gdb) break main
> Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
> (gdb) run
> Starting program: /tmp/a.out 
> 
> Breakpoint 1, main () at malloctest.c:5
> 5 p = malloc(16);
> (gdb) break malloc
> Breakpoint 2 at 0x80060e9a4: malloc. (2 locations)
> (gdb) cont
> Continuing.
> 
> Breakpoint 2, __malloc (size=16) at jemalloc_jemalloc.c:1636
> 1636  size_t usize JEMALLOC_CC_SILENCE_INIT(0);

gdb looks into debugging info for symbols in debug information and so
has greater visibility. Symbols gdb sees play no role in dynasmic
building, so rtld malloc somehow replacing the malloc from the program
as you suspected is really impossible.

kib@ has a better idea that is worth investigating further: is the
address on which idlc traps corresponds to TLS storage? tls alloc calls
are supposed to respect the tls section alignment though.

-- 
Alexander Kabaev


pgpz16Dbu9ryG.pgp
Description: Цифровая подпись OpenPGP

Re: malloc() call somehow calling the rtld malloc() implementaion

[Don Lewis]

On 27 Jan, Alexander Kabaev wrote:
> On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
> Don Lewis  wrote:

>> If I create a simple test program that calls malloc() and set a
>> breakpoint in malloc(), the breakpoint gets set in the rtld version,
>> but the the libc version of malloc is what gets called.
>> 
>> What the heck is going on here, and how can I fix it?
>> 
> 
> rtld on my system does not have malloc exposed as dynamic symbol, it
> cannot possibly be used for symbol resolution by any outside module.

Same here, but gdb at least seems to find it anyway.

12.0-CURRENT r311765M

%nm /libexec/ld-elf.so.1
nm: /libexec/ld-elf.so.1: no symbols

%elfdump -s /libexec/ld-elf.so.1 | grep st_name | sort
st_name: 
st_name: 
st_name: FBSD_1.0
st_name: FBSD_1.1
st_name: FBSD_1.2
st_name: FBSD_1.3
st_name: FBSD_1.4
st_name: FBSD_1.5
st_name: FBSDprivate_1.0
st_name: __tls_get_addr
st_name: _r_debug_postinit
st_name: _rtld_addr_phdr
st_name: _rtld_allocate_tls
st_name: _rtld_atfork_post
st_name: _rtld_atfork_pre
st_name: _rtld_error
st_name: _rtld_free_tls
st_name: _rtld_get_stack_prot
st_name: _rtld_is_dlopened
st_name: _rtld_thread_init
st_name: dl_iterate_phdr
st_name: dladdr
st_name: dlclose
st_name: dlerror
st_name: dlfunc
st_name: dlinfo
st_name: dllockinit
st_name: dlopen
st_name: dlsym
st_name: dlvsym
st_name: fdlopen
st_name: r_debug_state

%cd /tmp
zipper:/tmp 508%cat malloctest.c 
#include 
volatile void *p;
int
main(void) {
p = malloc(16);
}
%cc -g malloctest.c
%gdb a.out
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "amd64-marcel-freebsd"...
(gdb) break main
Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
(gdb) run
Starting program: /tmp/a.out 

Breakpoint 1, main () at malloctest.c:5
5   p = malloc(16);
Current language:  auto; currently minimal
(gdb) break malloc
Breakpoint 2 at 0x80060e9a4: file /usr/src/libexec/rtld-elf/malloc.c, line 163.
(gdb) cont
Continuing.

Program exited normally.
(gdb) quit

Ports gdb finds both the rtld malloc() and the libc malloc():

%/usr/local/bin/gdb a.out
GNU gdb (GDB) 7.12 [GDB v7.12 for FreeBSD]
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-portbld-freebsd12.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
.
Find the GDB manual and other documentation resources online at:
.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...done.
(gdb) break main
Breakpoint 1 at 0x40076b: file malloctest.c, line 5.
(gdb) run
Starting program: /tmp/a.out 

Breakpoint 1, main () at malloctest.c:5
5   p = malloc(16);
(gdb) break malloc
Breakpoint 2 at 0x80060e9a4: malloc. (2 locations)
(gdb) cont
Continuing.

Breakpoint 2, __malloc (size=16) at jemalloc_jemalloc.c:1636
1636size_t usize JEMALLOC_CC_SILENCE_INIT(0);

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Re: malloc() call somehow calling the rtld malloc() implementaion

[Konstantin Belousov]

On Fri, Jan 27, 2017 at 12:19:16PM -0500, Alexander Kabaev wrote:
> On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
> Don Lewis  wrote:
> 
> > I've been attempting to get OpenOffice to build properly in a
> > clang400-import poudriere jail and have run into a mystery.  The build
> > procedure creates a c++ executable "idlc", which is used to build
> > other stuff.  The new operator has been overrriden to call a custom
> > memory allocator, which I have configured to call the system version
> > of malloc().
> > 
> > At some point idlc crashes because it has allocated a 16 byte
> > structure and the compiler is using "movaps %xmm0,(%rax)" to
> > initialize it, which requires 16 byte alignment.  Unfortunately this
> > structure is only 8 byte aligned, causing a bus error.  This
> > shouldn't be happening because our system malloc() always seems to do
> > the proper alignment.  It appears that intead of calling the version
> > of malloc() in libc, the simple version of malloc() built into rtld
> > is being called instead.
> > 
> > GNU gdb 6.1.1 [FreeBSD]
> > Copyright 2004 Free Software Foundation, Inc.
> > GDB is free software, covered by the GNU General Public License, and
> > you are welcome to change it and/or distribute copies of it under
> > certain conditions. Type "show copying" to see the conditions.
> > There is absolutely no warranty for GDB.  Type "show warranty" for
> > details. This GDB was configured as "amd64-marcel-freebsd"...
> > (gdb) break main
> > Breakpoint 1 at 0x43b1f6: file idlcmain.cxx, line 34.
> > (gdb) run @/tmp/r
> > Starting
> > program: 
> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc
> > @/tmp/r [New LWP 101304] [New Thread 802616000 (LWP 101304/idlc)]
> > [Switching to Thread 802616000 (LWP 101304/idlc)]
> > 
> > Breakpoint 1, main (argc=2, argv=0x7fffb278) at idlcmain.cxx:34
> > 34  SAL_IMPLEMENT_MAIN_WITH_ARGS(argc, argv)
> > (gdb) break malloc
> > Breakpoint 2 at 0x8006a5f01:
> > file /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c,
> > line 163. (gdb) cont Continuing.
> > Trace 12474/1: "Min Prioriy for policy '2' == '0'
> > "
> > Trace 12474/1: "Max Prioriy for policy '2' == '103'
> > "
> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc:
> > compiling 1 source files ...
> > Compiling: 
> > /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/offapi/com/sun/star/i18n/KParseTokens.idl
> > 
> > Breakpoint 2, malloc (nbytes=343)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163 /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:
> > No such file or directory.
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > Current language:  auto; currently minimal (gdb) cont
> > Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=32)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > Trace 13112/2: "ChildStatusProc : starting
> > '/wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/ucpp'"
> >  [New
> > Thread 802616500 (LWP 100249/idlc)] [Switching to Thread 802616500
> > (LWP 100249/idlc)]
> > 
> > Breakpoint 2, malloc (nbytes=19)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=34)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=16)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=16)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=16)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > 
> > Breakpoint 2, malloc (nbytes=16)
> > at 
> > /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> > 163
> > in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> > (gdb) cont Continuing.
> > sizeof(AstExprValue)=16
> > 
> > Program received signal SIGBUS, Bus error.
> > [Switching to Thread 802616000 (LWP 101304/idlc)]
> > 0x00478cc2 in AstExpre

Re: malloc() call somehow calling the rtld malloc() implementaion

[Alexander Kabaev]

On Fri, 27 Jan 2017 00:31:30 -0800 (PST)
Don Lewis  wrote:

> I've been attempting to get OpenOffice to build properly in a
> clang400-import poudriere jail and have run into a mystery.  The build
> procedure creates a c++ executable "idlc", which is used to build
> other stuff.  The new operator has been overrriden to call a custom
> memory allocator, which I have configured to call the system version
> of malloc().
> 
> At some point idlc crashes because it has allocated a 16 byte
> structure and the compiler is using "movaps %xmm0,(%rax)" to
> initialize it, which requires 16 byte alignment.  Unfortunately this
> structure is only 8 byte aligned, causing a bus error.  This
> shouldn't be happening because our system malloc() always seems to do
> the proper alignment.  It appears that intead of calling the version
> of malloc() in libc, the simple version of malloc() built into rtld
> is being called instead.
> 
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and
> you are welcome to change it and/or distribute copies of it under
> certain conditions. Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for
> details. This GDB was configured as "amd64-marcel-freebsd"...
> (gdb) break main
> Breakpoint 1 at 0x43b1f6: file idlcmain.cxx, line 34.
> (gdb) run @/tmp/r
> Starting
> program: 
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc
> @/tmp/r [New LWP 101304] [New Thread 802616000 (LWP 101304/idlc)]
> [Switching to Thread 802616000 (LWP 101304/idlc)]
> 
> Breakpoint 1, main (argc=2, argv=0x7fffb278) at idlcmain.cxx:34
> 34SAL_IMPLEMENT_MAIN_WITH_ARGS(argc, argv)
> (gdb) break malloc
> Breakpoint 2 at 0x8006a5f01:
> file /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c,
> line 163. (gdb) cont Continuing.
> Trace 12474/1: "Min Prioriy for policy '2' == '0'
> "
> Trace 12474/1: "Max Prioriy for policy '2' == '103'
> "
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc:
> compiling 1 source files ...
> Compiling: 
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/offapi/com/sun/star/i18n/KParseTokens.idl
> 
> Breakpoint 2, malloc (nbytes=343)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163   /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:
> No such file or directory.
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> Current language:  auto; currently minimal (gdb) cont
> Continuing.
> 
> Breakpoint 2, malloc (nbytes=32)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> Trace 13112/2: "ChildStatusProc : starting
> '/wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/ucpp'"
>  [New
> Thread 802616500 (LWP 100249/idlc)] [Switching to Thread 802616500
> (LWP 100249/idlc)]
> 
> Breakpoint 2, malloc (nbytes=19)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> 
> Breakpoint 2, malloc (nbytes=34)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> 
> Breakpoint 2, malloc (nbytes=16)
> at 
> /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c:163
> 163
> in /var/poudriere/jails/clang400amd64/usr/src/libexec/rtld-elf/malloc.c
> (gdb) cont Continuing.
> sizeof(AstExprValue)=16
> 
> Program received signal SIGBUS, Bus error.
> [Switching to Thread 802616000 (LWP 101304/idlc)]
> 0x00478cc2 in AstExpression::eval_bit_op (this=0x802633dc8, 
> ek=EK_const) at astexpression.cxx:1001
> 1001  std::auto_ptr< AstExprValue > retval(new
> AstExprValue());
> 
> 
> idlc is linked to libc.so:
> 
> /wrkdirs/usr/ports/editors/openoffice-devel/work/aoo-4.2.0/main/solver/420/unxfbsdx.pro/bin/idlc:
>