question about segmentation fault error from address-sanitizer report

[laser]

Hi experts,

asan report segment fault error for memset line in the simple code below, valgrind doesn't report it, could you explain the reason?

  1 #include <signal.h>

  2 #include <stdio.h>

  3 #include <stdlib.h>

  4 #include <string.h>

  5

  6

  7 int main(void)

  8 {

  9     struct sigaction sa;

 10

 11     memset(&sa, 0, sizeof(sigaction));

 12     sigemptyset(&sa.sa_mask);

 13    // sa.sa_flags  = SA_SIGINFO;

 14

 15    // sigaction(SIGSEGV, &sa, NULL);

 16

 17     return 0;

 18 }

root@terry-lx:/tmp# ./segerror1

ASAN:SIGSEGV

=================================================================

==26565== ERROR: AddressSanitizer: SEGV on unknown address 0x17f91a12 (pc 0x0804868b sp 0xbfc8d060 bp 0xbfc8d158 T0)

AddressSanitizer can not provide additional info.

    #0 0x804868a (/tmp/segerror1+0x804868a)

    #1 0xb5fda4d2 (/lib/i386-linux-gnu/libc-2.15.so+0x194d2)

    #2 0x8048510 (/tmp/segerror1+0x8048510)

==26565== ABORTING

root@test-lx:/tmp# ./segerror1 2>&1 | ./asan_symbolize.py | c++filt

/tmp/llvm-3.4/llvm/Release+Asserts/bin/llvm-symbolizer --use-symbol-table=true --demangle=False --functions=true --inlining=true

ASAN:SIGSEGV

=================================================================

==26566== ERROR: AddressSanitizer: SEGV on unknown address 0x17ff0c3a (pc 0x0804868b sp 0xbff861a0 bp 0xbff86298 T0)

AddressSanitizer can not provide additional info.

    #0 0x804868a (/tmp/segerror1+0x804868a)

/tmp/segerror1 0x804868a

    #0 0x804868a in main /tmp/./segerror1.c:11:0

    #1 0xb60184d2 (/lib/i386-linux-gnu/libc-2.15.so+0x194d2)

/lib/i386-linux-gnu/libc-2.15.so 0x194d2

addr2line -f -e /lib/i386-linux-gnu/libc-2.15.so

/lib/i386-linux-gnu/libc-2.15.so 0x194d2

    #1 0xb60184d2 in __libc_start_main /build/buildd/eglibc-2.15/csu/libc-start.c:226

    #2 0x8048510 (/tmp/segerror1+0x8048510)

/tmp/segerror1 0x8048510

addr2line -f -e /tmp/segerror1

/tmp/segerror1 0x8048510

    #2 0x8048510 in _start ??:0

==26566== ABORTING

[Konstantin Serebryany]

This does not happen for me:

% cat z.c
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int main(void)
{
struct sigaction sa;

memset(&sa, 0, sizeof(sigaction));
sigemptyset(&sa.sa_mask);
// sa.sa_flags = SA_SIGINFO;

// sigaction(SIGSEGV, &sa, NULL);

return 0;
}
% clang z.c -fsanitize=address && ./a.out
%


Please provide more info. How do you compile? (make sure to add -g)
run this under gdb and show what 'bt' says.

--kcc

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[Dmitry Vyukov]

On Thu, Jan 16, 2014 at 7:14 AM, laser <sjzw...@gmail.com> wrote:

> Hi experts,
>
> asan report segment fault error for memset line in the simple code below,
> valgrind doesn't report it, could you explain the reason?
>
>
> 1 #include <signal.h>
> 2 #include <stdio.h>
> 3 #include <stdlib.h>
> 4 #include <string.h>
> 5
> 6
> 7 int main(void)
> 8 {
> 9 struct sigaction sa;
> 10
> 11 memset(&sa, 0, sizeof(sigaction));

try memset(&sa, 0, sizeof(sa));
sigaction may be referring to the function

[laser]

-g was added, The Compile info and gdb is below.  thanks!

 

<gcc4.8 path>/i686-linux5.0-gcc -fsanitize=address -g -Wl,-rpath=<libasan path>/lib -o segerror1 ./segerror1.c

(gdb) run

Starting program: /tmp/./segerror1

[Thread debugging using libthread_db enabled]

Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.

0x0804868b in main () at ./segerror1.c:11

11          memset(&sa, 0, sizeof(sigaction));

(gdb) bt

#0  0x0804868b in main () at ./segerror1.c:11

(gdb) bt full

#0  0x0804868b in main () at ./segerror1.c:11

        sa = {__sigaction_handler = {sa_handler = 0xbffff588, sa_sigaction = 0xbffff588}, sa_mask = {__val = {3087006324, 0, 3062103960, 1, 0, 1, 3087005976, 3061966280, 3061966288,

              3221222824, 3064042993, 3063833572, 3061050508, 3221222824, 3061014528, 3061094460, 3062313366, 0, 3064042993, 3221222916, 3061966280, 3064000985, 134518996, 134514512,

              0, 3221222776, 134514484, 3064105672, 3064104756, 3221222792, 134514653, 134514512}}, sa_flags = 134519256, sa_restorer = 0xbffff598}

[Konstantin Serebryany]

What happens if you follow Dmitry's suggestion?
sizeof(sigaction) is most likely not what you need.