Re: [Valgrind-users] Question: bug in user code, valgrind or glibc?

[John R. <jr...@bi...>]

> I sent a log of redirect information to both Paul and John since the log was too large was mailing list.
> 
> I wonder what would be the preferred public sharing site for such a purpose these days.

The preferred way is to create a bug report, attach the large file to the bug report,
then post the URL of the bug report in a message to the mailing list.

Begin at  https://valgrind.org/ .  In the left nav, click on "Bug Reports", and follow
the directions on the resulting page.


> 143:39.43 GECKO(115765) ==115769== Invalid read of size 8
> 143:39.64 GECKO(115765) ==115769==    at 0x4021BF4: strncmp (strcmp.S:175)
> 143:39.64 GECKO(115765) ==115769==    by 0x400655D: is_dst (dl-load.c:214) 

This indicates that 'strncmp' should be re-directed from ld-linux-x86-64.so.2:
=====
diff --git a/shared/vg_replace_strmem.c b/shared/vg_replace_strmem.c
index 3b42b3a87..8272a3ae7 100644
--- a/shared/vg_replace_strmem.c
+++ b/shared/vg_replace_strmem.c
@@ -710,6 +710,7 @@ static inline void my_exit ( int x )
   STRNCMP(VG_Z_LIBC_SONAME, __GI_strncmp)
   STRNCMP(VG_Z_LIBC_SONAME, __strncmp_sse2)
   STRNCMP(VG_Z_LIBC_SONAME, __strncmp_sse42)
+ STRNCMP("ld-linux*.so*", strncmp)

  #elif defined(VGO_freebsd)
   STRNCMP(VG_Z_LIBC_SONAME, strncmp)
=====
For instance, such a change is relevant to glibc-2.33-21.fc34.x86_64:
$ readelf --all /lib64/ld-linux-x86-64.so.2 | grep strncmp
   1706: 0000000000022d30  6233 FUNC    LOCAL  DEFAULT   13 strncmp
$