[Valgrind-developers] [PATCH] Intercept strncmp for glibc ld.so v2.28+

[Mike C. <ma...@mc...>]

In glibc 5aad5f617892e75d91d4c8fb7594ff35b610c042 (first released in
v2.28) a call to strncmp was added to dl-load.c:is_dst. This causes
valgrind to complain about glibc's highly-optimised strncmp performing
sixteen-byte reads on short strings in ld.so. Let's intercept strncmp in
ld.so too so we use valgrind's simple version to avoid this problem.
---
 shared/vg_replace_strmem.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/shared/vg_replace_strmem.c b/shared/vg_replace_strmem.c
index 87a4bcc55..5c05644fe 100644
--- a/shared/vg_replace_strmem.c
+++ b/shared/vg_replace_strmem.c
@@ -648,6 +648,8 @@ 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(VG_Z_LD_LINUX_SO_2, strncmp)
+ STRNCMP(VG_Z_LD_LINUX_X86_64_SO_2, strncmp)
 
 #elif defined(VGO_darwin)
  STRNCMP(VG_Z_LIBC_SONAME,        strncmp)
-- 
2.20.1