[Valgrind-users] About wrapper
Hello developers:
I want to write a tool for valgrind base on memcheck. I use the '_WRAP_
macros' to wrap malloc in libc, but there show me an error:
valgrind: m_redir.c:638 (vgPlain_redir_notify_new_DebugInfo): Assertion
'is_plausible_guest_addr(sym_avmas.main)' failed.
Segmentation fault (core dumped)
The code i add to 'mc_main.c' is:
long I_WRAP_SONAME_FNNAME_ZU(libcZdsoZd6,malloc) ( long n )
{
char * r;
OrigFn fn;
VALGRIND_GET_ORIG_FN(fn);
CALL_FN_W_W(r, fn, n);
//cloak_malloc_addr = r;
return r;
}
(I has already disable the malloc replacement by deleting
vgpreload_memcheck-amd64-linux.so.)
Thanks
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[Valgrind-users] how to change tmp value in dirty call
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[Valgrind-users] About how to get the guest code memory
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[Valgrind-users] About how to turn off the malloc hook
hello developers, I want to reuse the shadow memory part of memcheck , but do not want to use the malloc hook part. When I set the 'VG_(needs).malloc_replacement = False',the malloc hook part seems still to be working. Which code do I need to modify to make malloc replace invalid? -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
[Valgrind-users] How to invalidate the malloc replacement
hello developers, sorry to ask this question again. When i delete the 'VG_(needs_malloc_replacement) (MC_(malloc).)' , valgrind show me the error :'--7969-- VG_USERREQ__CLIENT_CALL1: func=0x0'. It seems that the replace system is still working,but don't know which address to call. so, what should i do to invalidate the malloc replacement ? plz. cloak -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
[Valgrind-users] About how to hook malloc to do sth and execute the original malloc
hello developer, i want to write a tool for valgrind to analysis an program automatically. I know that 'Memcheck's implementation of malloc has "nothing to do" with glibc's implementation' after readind some code of valgrind, but i want to use the glibc's malloc to avoid changing heap layout. Memcheck sets the VG_(needs_malloc_replacement) to hook malloc and exec MC_(malloc) instead of real malloc. It's very convenient. So can i get the address of the original malloc in MC_(malloc) and exec it? if not,can i use I_WRAP_SONAME_FNNAME_ZU function to hook malloc in my valgrind tool's code? thanks. -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
Re: [Valgrind-users] About how to hook malloc to do sth and execute the original malloc
thank you for your answer.
But when i use _WRAP_ macros like following code, it gives me an error.
*code:*
long I_WRAP_SONAME_FNNAME_ZU(libcZdsoZd6,malloc) ( long n )
{
char * r;
OrigFn fn;
printf("1\n");
VALGRIND_GET_ORIG_FN(fn);
CALL_FN_W_W(r, fn, n);
//printf("in wrapper1-post: fact(%d) = %x\n", n, r);
return r;
}
/* --- */
int main ( void )
{
char * r , *x, *y;
//printf("computing fact(5)\n");
//r = fact(5);
r = malloc(0x20);
x = malloc(0x20);
printf("malloc(0x20) = %x \n",r );
printf("malloc(0x20) = %x \n",x );
return 0;
}
* error:*
==14498== Stack overflow in thread #1: can't grow stack to 0xfe04d000
==14498==
==14498== Process terminating with default action of signal 11 (SIGSEGV)
==14498== Access not within mapped region at address 0xFE04DFFC
==14498== Stack overflow in thread #1: can't grow stack to 0xfe04d000
==14498==at 0x40B1183: _IO_doallocbuf (genops.c:394)
==14498== If you believe this happened as a result of a stack
==14498== overflow in your program's main thread (unlikely but
==14498== possible), you can try to increase the size of the
==14498== main thread stack using the --main-stacksize= flag.
==14498== The main thread stack size used in this run was 8388608.
But when i comment out the ' printf("1\n"); ', It seems ok.
On Thu, Jul 12, 2018 at 7:24 PM Tom Hughes wrote:
> On 12/07/18 10:26, shuai xi wrote:
>
> > I know that 'Memcheck's implementation of malloc has "nothing to do"
> > with glibc's implementation' after readind some code of valgrind, but i
> > want to use the glibc's malloc to avoid changing heap layout.
> > Memcheck sets the VG_(needs_malloc_replacement) to hook malloc and exec
> > MC_(malloc) instead of real malloc. It's very convenient. So can i
> > get the address of the original malloc in MC_(malloc) and exec it?
> > if not,can i use I_WRAP_SONAME_FNNAME_ZU function to hook malloc in my
> > valgrind tool's code?
>
> Yes if you want to wrap the function rather than replacing it
> then use the _WRAP_ macros and then your wrapper can get the
> original address and call it.
>
> Tom
>
> --
> Tom Hughes (t...@compton.nu)
> http://compton.nu/
>
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