[Bug libc/13583] New: AVX check not done correctly for strcasecmp

[Bug libc/13583] New: AVX check not done correctly for strcasecmp

[delroth at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13583

             Bug #: 13583
           Summary: AVX check not done correctly for strcasecmp
           Product: glibc
           Version: 2.15
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper.fsp@gmail.com
        ReportedBy: delroth@gmail.com
    Classification: Unclassified


According to Intel manuals, checking for AVX has to be done by checking AVX and
OS XSAVE support in CPUID + XFEATURE_ENABLED_MASK via xgetbv. However, for
strcasecmp, AVX is checked by testing the AVX bit in the cpuid.

This makes systems using glibc-2.15 unbootable under current versions of Xen
when the CPU supports AVX because Xen does not have XSAVE support. On these
systems, strcasecmp fails with a SIGILL when executing vmovdqa.

Bad check is here:
http://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/multiarch/strcmp.S;h=f93c83d7d469085029018dcf0d7f2eaadb05a44f;hb=HEAD#l108

Example of a good check:
http://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/dl-trampoline.S;h=6523c92945a59e6a5eefa3cfb2e0c58dfa99fd44;hb=HEAD#l137

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[allan at archlinux dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13583

Allan McRae <allan at archlinux dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |allan at archlinux dot org

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13583

Ulrich Drepper <drepper.fsp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #1 from Ulrich Drepper <drepper.fsp at gmail dot com> 2012-01-26 12:46:20 UTC ---
I checked in a patch.

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13583

--- Comment #2 from Ulrich Drepper <drepper.fsp at gmail dot com> 2012-01-26 14:48:35 UTC ---
Actually, strcmp cannot have problems since the code only uses the AVX
instruction encoding, not the YMM registers.  Therefore any problem in that
area must have a completely different reason.  There is code which potentially
uses the YMM registers and I added protection there.

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[jackie.rosen at hushmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=13583

Jackie Rosen <jackie.rosen at hushmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jackie.rosen at hushmail dot com

--- Comment #3 from Jackie Rosen <jackie.rosen at hushmail dot com> ---
*** Bug 260998 has been marked as a duplicate of this bug. ***
Seen from the domain http://volichat.com
Page where seen: http://volichat.com/adult-chat-rooms
Marked for reference. Resolved as fixed @bugzilla.

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[schwab at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=13583

Andreas Schwab <schwab at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|jackie.rosen at hushmail dot com   |

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[Bug libc/13583] AVX check not done correctly for strcasecmp

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=13583

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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