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Date: Thu, 14 Jul 2011 12:41:35 +0200
From: Luka Marčetić <paxcoder@...il.com>
To: musl@...ts.openwall.com
Subject: Re: cluts: strerror_r() test
On 07/14/2011 11:57 AM, Solar Designer wrote:
> Luka, Rich -
>
> I've uncommented the test for strerror_r(), which you marked "glibc
> fail", and it passed the test on glibc 2.3.6 for me. What exactly was
> wrong with it (or rather with glibc) in your testing?
>
> Thanks,
>
> Alexander
The test was uncommented yesterday morning, as I found it was my fault
that it crashed, not glibc's. Actually, I think it was -O2 that helped
me realize that, after I had uncommented the function. Here's the
relevant diff:
https://github.com/lmarcetic/cluts/commit/803ebc888ebe6656287034739229baa93376d0fc#tests/buf.c
You can see that strerror_r was passed size-1, although size was not
initialized (or rather, it was initialized by a test before that one).
Strerror_r implementations are free to redirect a passed pointer to
immutable memory if size(buflen) argument is sufficiently large. Of
course, wanting to write to s[size-1] would SIGSEGV in that case. My
assumption was that glibc redirected the pointer even though I gave it
size-1, in which case it's incorrect behavior and it should simply copy
to the provided buffer. Turns out that's not the case, and the fail was
mine.
Luka.
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