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

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Mar 16, 2011, 10:52 UTC
Message-ID: <20110316105214.GB8277@elie>
In-Reply-To: <1300272453-25891-1-git-send-email-cmn@elego.de>

Carlos Martín Nieto wrote:

Show 5 quoted lines

> The GNU C Library (glibc) uses SSE instructions to make strlen (among
> others) faster, loading 4 bytes at a time and reading past the end of
> the allocated memory. This read is safe and when the strlen function
> is inlined, it is (obviously) not replaced by valgrind, which reports
> a false-possitive.

This still makes no sense to me. How is it possible to inline a function from glibc? When I look in /usr/include/string.h, I see

extern size_t strlen (__const char *__s)
     __THROW __attribute_pure__ __nonnull ((1));

> Tell valgrind to ignore this particular error, as the read is, in
> fact, safe.

I'm happy to see a workaround. I would be even happier if it came with documentation about which versions of valgrind need it.

Thanks again. Jonathan