Re: [Qemu-devel] [PATCH for-2.12] gdbstub: fix off-by-one in gdb_handle_packet()

2018-04-09 Thread Peter Maydell
On 9 April 2018 at 10:39, Paolo Bonzini  wrote:
> On 09/04/2018 07:58, Stefan Hajnoczi wrote:
>> On Sun, Apr 08, 2018 at 11:59:33AM -0300, Philippe Mathieu-Daudé wrote:
>>> memtohex() adds an extra trailing NUL character.
>>>
>>> Reported-by: AddressSanitizer
>>> Signed-off-by: Philippe Mathieu-Daudé 
>>> ---
>>> (gdb) dump binary memory /tmp/dram.bin 0x9400 0x9410
>>> Remote connection closed
>>>
>>> =
>>> ==22732==ERROR: AddressSanitizer: stack-buffer-overflow on address 
>>> 0x7ffe43018340 at pc 0x55f2655fde81 bp 0x7ffe43017210 sp 0x7ffe43017208
>>> WRITE of size 1 at 0x7ffe43018340 thread T0
>>>
>>> ---
>>>  gdbstub.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> Reviewed-by: Stefan Hajnoczi 
>
> Peter, can you apply this directly to master?

Applied, thanks. (patchwork and patches made a pig's ear of this
for some reason, I think they got confused about where the
commit message stopped and the patch started, so I had to
hand-edit the files.)

-- PMM



Re: [Qemu-devel] [PATCH for-2.12] gdbstub: fix off-by-one in gdb_handle_packet()

2018-04-09 Thread Paolo Bonzini
On 09/04/2018 07:58, Stefan Hajnoczi wrote:
> On Sun, Apr 08, 2018 at 11:59:33AM -0300, Philippe Mathieu-Daudé wrote:
>> memtohex() adds an extra trailing NUL character.
>>
>> Reported-by: AddressSanitizer
>> Signed-off-by: Philippe Mathieu-Daudé 
>> ---
>> (gdb) dump binary memory /tmp/dram.bin 0x9400 0x9410
>> Remote connection closed
>>
>> =
>> ==22732==ERROR: AddressSanitizer: stack-buffer-overflow on address 
>> 0x7ffe43018340 at pc 0x55f2655fde81 bp 0x7ffe43017210 sp 0x7ffe43017208
>> WRITE of size 1 at 0x7ffe43018340 thread T0
>>
>> ---
>>  gdbstub.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Reviewed-by: Stefan Hajnoczi 

Peter, can you apply this directly to master?

Thanks,

Paolo



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Re: [Qemu-devel] [PATCH for-2.12] gdbstub: fix off-by-one in gdb_handle_packet()

2018-04-08 Thread Stefan Hajnoczi
On Sun, Apr 08, 2018 at 11:59:33AM -0300, Philippe Mathieu-Daudé wrote:
> memtohex() adds an extra trailing NUL character.
> 
> Reported-by: AddressSanitizer
> Signed-off-by: Philippe Mathieu-Daudé 
> ---
> (gdb) dump binary memory /tmp/dram.bin 0x9400 0x9410
> Remote connection closed
> 
> =
> ==22732==ERROR: AddressSanitizer: stack-buffer-overflow on address 
> 0x7ffe43018340 at pc 0x55f2655fde81 bp 0x7ffe43017210 sp 0x7ffe43017208
> WRITE of size 1 at 0x7ffe43018340 thread T0
> #0 0x55f2655fde80 in memtohex /source/qemu/gdbstub.c:520
> #1 0x55f26560254d in gdb_handle_packet /source/qemu/gdbstub.c:1140
> #2 0x55f2656073c3 in gdb_read_byte /source/qemu/gdbstub.c:1703
> #3 0x55f2656076a7 in gdb_chr_receive /source/qemu/gdbstub.c:1909
> #4 0x55f266457656 in qemu_chr_be_write_impl 
> /source/qemu/chardev/char.c:175
> #5 0x55f2664576f9 in qemu_chr_be_write /source/qemu/chardev/char.c:187
> #6 0x55f26646f6f0 in tcp_chr_read /source/qemu/chardev/char-socket.c:470
> #7 0x55f2664bc9e3 in qio_channel_fd_source_dispatch 
> /source/qemu/io/channel-watch.c:84
> #8 0x7f17d01b30f4 in g_main_context_dispatch 
> (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x4c0f4)
> #9 0x55f2665c7f10 in glib_pollfds_poll /source/qemu/util/main-loop.c:215
> #10 0x55f2665c8100 in os_host_main_loop_wait 
> /source/qemu/util/main-loop.c:263
> #11 0x55f2665c82d6 in main_loop_wait /source/qemu/util/main-loop.c:522
> #12 0x55f26599e13b in main_loop /source/qemu/vl.c:1943
> #13 0x55f2659b0869 in main /source/qemu/vl.c:4734
> 
> Address 0x7ffe43018340 is located in stack of thread T0 at offset 4192 in 
> frame
> #0 0x55f265601266 in gdb_handle_packet /source/qemu/gdbstub.c:996
> 
>   This frame has 3 object(s):
> [32, 40) 'p'
> [96, 4192) 'buf' <== Memory access at offset 4192 overflows this variable
> [4224, 8320) 'mem_buf'
> SUMMARY: AddressSanitizer: stack-buffer-overflow /source/qemu/gdbstub.c:520 
> in memtohex
> Shadow bytes around the buggy address:
>   0x1000485fb010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> =>0x1000485fb060: 00 00 00 00 00 00 00 00[f2]f2 f2 f2 00 00 00 00
>   0x1000485fb070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb0a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x1000485fb0b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> Shadow byte legend (one shadow byte represents 8 application bytes):
>   Addressable:   00
>   Partially addressable: 01 02 03 04 05 06 07
>   Heap left redzone:   fa
>   Freed heap region:   fd
>   Stack left redzone:  f1
>   Stack mid redzone:   f2
>   Stack right redzone: f3
>   Stack after return:  f5
>   Stack use after scope:   f8
>   Global redzone:  f9
>   Global init order:   f6
>   Poisoned by user:f7
>   Container overflow:  fc
>   Array cookie:ac
>   Intra object redzone:bb
>   ASan internal:   fe
>   Left alloca redzone: ca
>   Right alloca redzone:cb
> ==22732==ABORTING
> ---
>  gdbstub.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi 


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[Qemu-devel] [PATCH for-2.12] gdbstub: fix off-by-one in gdb_handle_packet()

2018-04-08 Thread Philippe Mathieu-Daudé
memtohex() adds an extra trailing NUL character.

Reported-by: AddressSanitizer
Signed-off-by: Philippe Mathieu-Daudé 
---
(gdb) dump binary memory /tmp/dram.bin 0x9400 0x9410
Remote connection closed

=
==22732==ERROR: AddressSanitizer: stack-buffer-overflow on address 
0x7ffe43018340 at pc 0x55f2655fde81 bp 0x7ffe43017210 sp 0x7ffe43017208
WRITE of size 1 at 0x7ffe43018340 thread T0
#0 0x55f2655fde80 in memtohex /source/qemu/gdbstub.c:520
#1 0x55f26560254d in gdb_handle_packet /source/qemu/gdbstub.c:1140
#2 0x55f2656073c3 in gdb_read_byte /source/qemu/gdbstub.c:1703
#3 0x55f2656076a7 in gdb_chr_receive /source/qemu/gdbstub.c:1909
#4 0x55f266457656 in qemu_chr_be_write_impl /source/qemu/chardev/char.c:175
#5 0x55f2664576f9 in qemu_chr_be_write /source/qemu/chardev/char.c:187
#6 0x55f26646f6f0 in tcp_chr_read /source/qemu/chardev/char-socket.c:470
#7 0x55f2664bc9e3 in qio_channel_fd_source_dispatch 
/source/qemu/io/channel-watch.c:84
#8 0x7f17d01b30f4 in g_main_context_dispatch 
(/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x4c0f4)
#9 0x55f2665c7f10 in glib_pollfds_poll /source/qemu/util/main-loop.c:215
#10 0x55f2665c8100 in os_host_main_loop_wait 
/source/qemu/util/main-loop.c:263
#11 0x55f2665c82d6 in main_loop_wait /source/qemu/util/main-loop.c:522
#12 0x55f26599e13b in main_loop /source/qemu/vl.c:1943
#13 0x55f2659b0869 in main /source/qemu/vl.c:4734

Address 0x7ffe43018340 is located in stack of thread T0 at offset 4192 in frame
#0 0x55f265601266 in gdb_handle_packet /source/qemu/gdbstub.c:996

  This frame has 3 object(s):
[32, 40) 'p'
[96, 4192) 'buf' <== Memory access at offset 4192 overflows this variable
[4224, 8320) 'mem_buf'
SUMMARY: AddressSanitizer: stack-buffer-overflow /source/qemu/gdbstub.c:520 in 
memtohex
Shadow bytes around the buggy address:
  0x1000485fb010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x1000485fb060: 00 00 00 00 00 00 00 00[f2]f2 f2 f2 00 00 00 00
  0x1000485fb070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb0a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000485fb0b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:   00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:   fa
  Freed heap region:   fd
  Stack left redzone:  f1
  Stack mid redzone:   f2
  Stack right redzone: f3
  Stack after return:  f5
  Stack use after scope:   f8
  Global redzone:  f9
  Global init order:   f6
  Poisoned by user:f7
  Container overflow:  fc
  Array cookie:ac
  Intra object redzone:bb
  ASan internal:   fe
  Left alloca redzone: ca
  Right alloca redzone:cb
==22732==ABORTING
---
 gdbstub.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gdbstub.c b/gdbstub.c
index a76b2fa481..18a8d8a710 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -507,6 +507,7 @@ static inline int tohex(int v)
 return v - 10 + 'a';
 }
 
+/* writes 2*len+1 bytes in buf */
 static void memtohex(char *buf, const uint8_t *mem, int len)
 {
 int i, c;
@@ -999,8 +1000,9 @@ static int gdb_handle_packet(GDBState *s, const char 
*line_buf)
 const char *p;
 uint32_t thread;
 int ch, reg_size, type, res;
-char buf[MAX_PACKET_LENGTH];
 uint8_t mem_buf[MAX_PACKET_LENGTH];
+char buf[sizeof(mem_buf) + 1 /* trailing NUL */];
 uint8_t *registers;
 target_ulong addr, len;
 
-- 
2.17.0