[Bug libc/16462] New: memcpy corrupted the data

[Bug libc/16462] New: memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

            Bug ID: 16462
           Summary: memcpy corrupted the data
           Product: glibc
           Version: 2.18
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: glin at suse dot com
                CC: drepper.fsp at gmail dot com

While building OVMF with glibc 2.18, some data in the intermediate C file were
corrupted. With git bisect, the culprit was identified:

https://sourceware.org/git/?p=glibc.git;a=commit;h=2d48b41c8fa610067c4d664ac2339ae6ca43e78c

After reverting the patch, everything works again.

Steps to reproduce:
1. clone the edk2 source code from https://github.com/tianocore/edk2

2. build the utility program with glibc 2.18
$ make -C BaseTools/

3. generate the intermediate C file with the attached files
./BaseTools/Source/C/bin/VfrCompile -l -n --string-db
SecureBootConfigDxeStrDefs.hpk --output-directory . SecureBootConfig.i

4. compare the generated SecureBootConfig.c with the correct one (attached
later)

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[Bug libc/16462] memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

--- Comment #1 from Gary Lin <glin at suse dot com> ---
Created attachment 7359
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7359&action=edit
SecureBootConfigDxeStrDefs.hpk

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[Bug libc/16462] memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

--- Comment #2 from Gary Lin <glin at suse dot com> ---
Created attachment 7360
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7360&action=edit
SecureBootConfig.i

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[Bug libc/16462] memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

--- Comment #3 from Gary Lin <glin at suse dot com> ---
Created attachment 7361
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7361&action=edit
expected SecureBootConfig.c

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[Bug libc/16462] memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

--- Comment #4 from Gary Lin <glin at suse dot com> ---
Created attachment 7362
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7362&action=edit
OVMF patch to workaround the bug

It seems only one line in BaseTools/Source/C/VfrCompile/VfrFormPkg.cpp is
really affected. Replacing memcpy in the line with my own memcpy fixed my
problem.

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[Bug libc/16462] memcpy corrupted the data

[aj at suse dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

Andreas Jaeger <aj at suse dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aj at suse dot de

--- Comment #5 from Andreas Jaeger <aj at suse dot de> ---
Change is:

Faster memcpy on x64.

We add new memcpy version that uses unaligned loads which are fast
on modern processors. This allows second improvement which is avoiding
computed jump which is relatively expensive operation.

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[Bug libc/16462] memcpy corrupted the data

[aj at suse dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

Andreas Jaeger <aj at suse dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |neleai at seznam dot cz

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[Bug libc/16462] memcpy corrupted the data

[glin at suse dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

Gary Lin <glin at suse dot com> changed:

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

--- Comment #6 from Gary Lin <glin at suse dot com> ---
I found the line caused the problem actually copied the overlapped buffer, and
the new memcpy exposed the bug. Sorry for the noise.

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[Bug libc/16462] memcpy corrupted the data

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

--- Comment #7 from Andreas Schwab <schwab@linux-m68k.org> ---
valgrind can find such problems.

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[Bug libc/16462] memcpy corrupted the data

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16462

Florian Weimer <fweimer at redhat dot com> changed:

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

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