src/patches/glibc/glibc-rh846342.patch

   1 This is a workaround for broken code which issues memcpy requests with
   2 overlapping arguments.  With this patch installed, if the file
   3 /etc/sysconfig/32bit_ssse3_memcpy_via_32bit_ssse3_memmove exists then a
   4 32bit memcpy call which normally would be handled by the SSSE3 memcpy
   5 implementation would instead be handled by the 32bit SSSE3 memmove
   6 implementation which is more tolerant of overlaps.
   7
   8 diff -Nrup a/sysdeps/i386/i686/multiarch/memcpy.S b/sysdeps/i386/i686/multiarch/memcpy.S
   9 --- a/sysdeps/i386/i686/multiarch/memcpy.S      2010-05-04 05:27:23.000000000 -0600
  10 +++ b/sysdeps/i386/i686/multiarch/memcpy.S      2012-11-20 14:19:52.890780415 -0700
  11 @@ -21,6 +21,10 @@
  12  #include <sysdep.h>
  13  #include <init-arch.h>
  14
  15 +        .section .rodata
  16 +L(magicfile):
  17 +       .ascii "/etc/sysconfig/32bit_ssse3_memcpy_via_32bit_ssse3_memmove"
  18 +
  19  /* Define multiple versions only for the definition in lib and for
  20     DSO.  In static binaries we need memcpy before the initialization
  21     happened.  */
  22 @@ -48,6 +52,26 @@ ENTRY(memcpy)
  23  1:     leal    __memcpy_ia32@GOTOFF(%ebx), %eax
  24         testl   $bit_SSSE3, CPUID_OFFSET+index_SSSE3+__cpu_features@GOTOFF(%ebx)
  25         jz      2f
  26 +
  27 +       /* This is an inlined access (magicfile, 0) syscall.
  28 +
  29 +          Note that it clobbers %ebx, so we have to save/restore
  30 +          it around the syscall.  */
  31 +       mov     %ebx, %edx
  32 +       leal    L(magicfile)@GOTOFF(%ebx), %ebx
  33 +       xor     %ecx, %ecx
  34 +       movl    $33, %eax
  35 +       int     $0x80
  36 +       mov     %edx, %ebx
  37 +
  38 +       /* If the file did not exist, then %eax will be -1..-4095 and we
  39 +          do nothing special.  */
  40 +       cmpl    $-4095, %eax
  41 +       jae     4f
  42 +
  43 +       leal    __memmove_ssse3@GOTOFF(%ebx), %eax
  44 +       jmp     2f
  45 +4:
  46         leal    __memcpy_ssse3@GOTOFF(%ebx), %eax
  47         testl   $bit_Fast_Rep_String, FEATURE_OFFSET+index_Fast_Rep_String+__cpu_features@GOTOFF(%ebx)
  48         jz      2f