[PATCH] valgrind: ignore SSE-based strlen invalid reads

["Carlos Martín Nieto" <cmn@elego.de>]

Some versions of strlen use SSE to speed up the calculation and load 4
bytes at a time, even if it means reading past the end of the
allocated memory. This read is safe and when the strlen function is
inlined, it is not replaced by valgrind, which reports a
false-possitive.

Tell valgrind to ignore this particular error, as the read is, in
fact, safe. Current upstream-released version 2.6.1 is affected. Some
distributions have this fixed in their latest versions.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
---

>>  I think 3.6.1 doesn't need it, as Debian's 1:3.5.0+3.6.0svn20100609-1
>> version is reportedly fixed.
>
>Ah, nice.  A phrase like "some versions of valgrind before 3.6.1"
>would be fine with me fwiw. :)

I just downloaded and compiled the upstream release 2.6.1 and it's
still affected (it does fix some other related
false-positives). Fedorea rawhide has the fix in, according to their
bug tracker. I haven't tested the reportedly-fixed version in Debian
yet.

 t/valgrind/default.supp |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/t/valgrind/default.supp b/t/valgrind/default.supp
index 9e013fa..327478c 100644
--- a/t/valgrind/default.supp
+++ b/t/valgrind/default.supp
@@ -43,3 +43,9 @@
 	fun:write_buffer
 	fun:write_loose_object
 }
+
+{
+	ignore-sse-strlen-invalid-read-size
+	Memcheck:Addr4
+	fun:copy_ref
+}
\ No newline at end of file
-- 
1.7.4.1