Integer signedness error in Glibc before 2.13 and eglibc before 2.13, when using Supplemental Streaming SIMD Extensions 3 (SSSE3) optimization, allows context-dependent attackers to execute arbitrary code via a negative length parameter to (1) memcpy-ssse3-rep.S, (2) memcpy-ssse3.S, or (3) memset-sse2.S in sysdeps/i386/i686/multiarch/, which triggers an out-of-bounds read, as demonstrated using the memcpy function.
https://sourceware.org/git/?p=glibc.git%3Ba=commit%3Bh=a0ac24d98ace90d1ccba6a2f3e7d55600f2fdb6e
https://bugzilla.novell.com/show_bug.cgi?id=706915
http://www.nodefense.org/eglibc.txt
http://www.eglibc.org/cgi-bin/viewvc.cgi/trunk/libc/ChangeLog?view=markup&pathrev=10032