[Bug libc/16554] New: memset incorrect for negative signed char

[Bug libc/16554] New: memset incorrect for negative signed char

[geoff at dyalog dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=16554

            Bug ID: 16554
           Summary: memset incorrect for negative signed char
           Product: glibc
           Version: 2.13
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: geoff at dyalog dot com
                CC: drepper.fsp at gmail dot com

memset() for the ARM does not honour the "converted to an unsigned char"
required by 7.21.6.1 of ISO/IEC 9899:1999(E)

signed char smallint = -3;
signed char smallarray[10];

memset(smallarray, smallint, 10);

results in smallarray[0] ←→ -3
           smallarray[1] ←→ -1
           smallarray[2] ←→ -1
           smallarray[3] ←→ -1
           smallarray[4] ←→ -3
...
code widens the smallint of -3 to int with sign extension - correctly. memset()
fails to AND this with 0xff before shifting and ORing.

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From: "neleai at seznam dot cz" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug libc/16554] [arm] memset incorrect for negative signed char
Date: Tue, 11 Feb 2014 12:21:00 -0000
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https://sourceware.org/bugzilla/show_bug.cgi?id\x16554

Ondrej Bilka <neleai at seznam dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |neleai at seznam dot cz
            Summary|memset incorrect for        |[arm] memset incorrect for
                   |negative signed char        |negative signed char

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[Bug libc/16554] [arm] memset incorrect for negative signed char

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16554

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

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

--- Comment #1 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
Such a bug was fixed in 2005:

commit a7ed1adbecb6aac49af75aae3b3498798cf63abc
Author: Daniel Jacobowitz <dan@codesourcery.com>
Date:   Mon Oct 10 15:00:47 2005 +0000

        * sysdeps/arm/memset.S (memset): Correct handling of negative
        arguments.

(I am doubtful of the reported version 2.13, which is a lot more recent than
that.)

If you see this with current glibc (2.19 or current git), please give a
complete compilable self-contained testcase, not code fragments, with details
of how glibc was configured.

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[Bug libc/16554] [arm] memset incorrect for negative signed char

[geoff at dyalog dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16554

--- Comment #2 from Geoff Streeter <geoff at dyalog dot com> ---
Might be blaming the wrong people here - sorry.

Using a standard Raspberian and it looks like the dodgy implementation of
memset is in a library called
libcofi_rpi.so, which gets loaded automatically because /etc/ld.so.preload
contains the line:

/usr/lib/arm-linux-gnueabihf/libcofi_rpi.so

The source code for libcofi_rpi.so seems to come from this project, where you
can see that the implementation of memset doesn't start with anything like "and
r1,r1,#0xff":

https://github.com/bavison/arm-mem 

I will log a bug against that project.

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[Bug libc/16554] [arm] memset incorrect for negative signed char

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16554

Florian Weimer <fweimer at redhat dot com> changed:

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

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