Re: [PATCH] Serious glibc sparc rlimits bug
On Sun, Aug 14, 2011 at 12:29:18AM -0700, David Miller wrote:
>
> Unfortunately, the sparc32 definition of the 64-bit RLIM_INFINITY
> value is wrong, and it's been wrong for a while.
>
> This causes serious problems, the worst of which is that no 64-bit
> pthread program executing as a child of 'make' can succeed.
>
> GLIBC's pthread_create() uses the current RLIMIT_STACK value as a hint
> for sizing thread stacks. It handles RLIM_INFINITY specially instead
> of trying to allocate an enormous stack.
>
> But if RLIM_INFINITY is wrong... right, nothing works.
>
> How this happens is that libpam corrupts the kernel default rlimits
> when it creates a login session, because even if you have no explicit
> settings in /etc/security/limits.conf it still reads every rlimit
> then sets it right back to the same value. It even has some pre-cooked
> defaults, and the default for RLIMIT_STACK is cur=8MB max=RLIM_INFINITY
>
> So if RLIM_INFINITY is wrong (for 32-bit binaries it's too small), the
> values will all get truncated down to this incorrect RLIM_INFINITY
> value.
>
> Next, make sets the current RLIMIT_STACK 'cur' value to the maximum,
> so now the current RLIMIT_STACK has this wrong RLIM_INFINITY value
> too.
>
> Then 64-bit glibc doesn't recognize this value as RLIM_INFINITY during
> pthread_create() and it tries to allocate a thread stack of size
> 0x8000000000000000 bytes. This, of course, fails.
>
> A bunch of binaries are going to need to be rebuilt because of this issue
> once the glibc build goes through, I would prioritize libpam0g, make,
> and emacs23.
>
> I'll be committing this soon to glibc GIT. I tested this by doing a
> glibc deb rebuild with this patch applied, installing, then rebuilding
> libpam0g and make.
Thanks for the information and the fix. I've opened a bug to keep
track of the issue:
http://bugs.debian.org/637767
If you have any references to upstream bug or commit(s), please add them
to it.
>
> 2011-08-14 David S. Miller <davem@davemloft.net>
>
> * sysdeps/unix/sysv/linux/sparc/bits/resource.h (RLIM_INFINITY,
> RLIM64_INFINITY): Fix 64-bit values for 32-bit sparc.
>
> diff --git a/sysdeps/unix/sysv/linux/sparc/bits/resource.h b/sysdeps/unix/sysv/linux/sparc/bits/resource.h
> index 04d33e4..5c00b8f 100644
> --- a/sysdeps/unix/sysv/linux/sparc/bits/resource.h
> +++ b/sysdeps/unix/sysv/linux/sparc/bits/resource.h
> @@ -130,11 +130,11 @@ enum __rlimit_resource
> #ifndef __USE_FILE_OFFSET64
> # define RLIM_INFINITY ((long int)(~0UL >> 1))
> #else
> -# define RLIM_INFINITY 0x7fffffffffffffffLL
> +# define RLIM_INFINITY 0xffffffffffffffffLL
> #endif
>
> #ifdef __USE_LARGEFILE64
> -# define RLIM64_INFINITY 0x7fffffffffffffffLL
> +# define RLIM64_INFINITY 0xffffffffffffffffLL
> #endif
>
> #endif
--
Jurij Smakov jurij@wooyd.org
Key: http://www.wooyd.org/pgpkey/ KeyID: C99E03CC
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