[Bug libc/12077] strncmp over-reads its buffer, may cause SIGSEGV

["ppluzhnikov at google dot com" <sourceware-bugzilla@sourceware.org>]

------- Additional Comments From ppluzhnikov at google dot com  2010-10-01 14:00 -------
(In reply to comment #2)
> Why can't you be specific and describe exactly what type of machine you're using?

Sorry. The crash shows on every x86_64 linux machine I have tried.

Here is /proc/cpuinfo from one:

processor	: 0
vendor_id	: AuthenticAMD
cpu family	: 15
model		: 65
model name	: Dual-Core AMD Opteron(tm) Processor 8214 HE
stepping	: 2
cpu MHz		: 2200.000
cache size	: 1024 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 2
fpu		: yes
fpu_exception	: yes
cpuid level	: 1
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow
rep_good pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy
bogomips	: 4420.36
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc


> You better know meanwhile that there are multiple implementations available.

Right, sorry about it. On above AMD, the crash is here:

(gdb) r 15
region 1: [0x7ffff7ff4000, 0x7ffff7ff5000)
region 2: [0x7ffff7ff2000, 0x7ffff7ff4000)
strncmp(0x7ffff7ff400f, 0x7ffff7ff200f, 4081) = 0

Program received signal SIGSEGV, Segmentation fault.
__strncmp_sse2 () at ../sysdeps/x86_64/multiarch/../strcmp.S:2149
2149		movdqa	(%rdi, %rcx), %xmm2

Same on model name    : Intel(R) Pentium(R) 4 CPU 3.40GHz

On model name    : Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc
arch_perfmon pebs bts rep_good aperfmperf pni dtes64 monitor ds_cpl vmx est tm2
ssse3 cx16 xtpr pdcm lahf_lm tpr_shadow

the crash is here:

(gdb) r 15
region 1: [0x7ffff7ff5000, 0x7ffff7ff6000)
region 2: [0x7ffff7ff3000, 0x7ffff7ff5000)
strncmp(0x7ffff7ff500f, 0x7ffff7ff300f, 4081) = 0

Program received signal SIGSEGV, Segmentation fault.
__strncmp_ssse3 () at ../sysdeps/x86_64/multiarch/../strcmp.S:2149
2149	../sysdeps/x86_64/multiarch/../strcmp.S: No such file or directory.
	in ../sysdeps/x86_64/multiarch/../strcmp.S

I can't find any SSE4 machines at the moment.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=12077

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