Testing valgrind in rawhide (separate valgrind-debuginfo package)

[Mark Wielaard]

On Thu, 2013-03-07 at 13:42 +0100, Jan Kratochvil wrote:
> On Wed, 06 Mar 2013 15:38:54 +0100, Richard W.M. Jones wrote:
> > ==11843== 56 bytes in 1 blocks are definitely lost in loss record 6 of 6
> > ==11843==    at 0x4A06409: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> > ==11843==    by 0x38EAC861F9: strdup (strdup.c:42)
> > ==11843==    by 0x38EC8097C9: setprocattrcon_raw.constprop.3 (procattr.c:241)
> > ==11843==    by 0x38EC8099B7: setprocattrcon.constprop.2 (procattr.c:274)
> > ==11843==    by 0x400955: main (in /tmp/test)
> > 
> > The symbol we're actually calling is 'setsockcreatecon'.  It's not a
> > macro.  There is no public function called 'setprocattrcon'
> [...]
> On Thu, 07 Mar 2013 10:10:56 +0100, Mark Wielaard wrote:
> > Though note that the name we were really looking for was
> > setsockcreatecon, since that is what was called from main. I think that
> > one is doing a tail-call to setprocattrcon.constprop.2 so might not
> > easily be available in the backtrace. If you compile and run Richard's
> > reproducer from https://bugzilla.redhat.com/show_bug.cgi?id=918572 and
> > break at the strdup call, can you get a backtrace from gdb with
> > setsockcreatecon in it?
> 
> Yes:
> 
> (gdb) bt
> #0  __GI___strdup (s=0x6021e0 "unconfined_u:unconfined_r:svirt_socket_t:s0-s0:c0.c1023") at strdup.c:40
> #1  0x00007ffff7bc27ca in setprocattrcon_raw (context=0x6021e0 "unconfined_u:unconfined_r:svirt_socket_t:s0-s0:c0.c1023", 
>     attr=attr at entry=0x7ffff7bd11f6 "sockcreate", pid=0) at procattr.c:241
> #2  0x00007ffff7bc29b8 in setprocattrcon (context=<optimized out>, attr=attr at entry=0x7ffff7bd11f6 "sockcreate", pid=0) at procattr.c:274
> #3  0x00007ffff7bc2ddc in setsockcreatecon (c=<optimized out>) at procattr.c:320
> #4  0x0000000000400818 in main () at constprop.c:33
> (gdb) info frame 3
> Stack frame at 0x7fffffffe130:
>  rip = 0x7ffff7bc2ddc in setsockcreatecon (procattr.c:320); saved rip 0x7ffff781ab75
>  tail call frame, caller of frame at 0x7fffffffe130
>  ^^^^^^^^^^^^^^^
>  source language c.
>  Arglist at unknown address.
>  Locals at unknown address, Previous frame's sp is 0x7fffffffe130
> 
> But one has to compile the main program with -O2 -g so that it has the needed
> call site debug information:
> 	gcc -Wall constprop.c -o constprop -lselinux -g -O2

O, very nice! It is kind of funny that gcc generates better/fuller
debuginfo with higher optimizations these days.

Currently valgrind doesn't handle DW_TAG_GNU_call_site at all. But if
people install debuginfo anyway to get better backtraces and/or symbol
resolution it might make sense to teach valgrind about it.

Thanks,

Mark