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x86/lib: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S

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  393f203f5f ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")

added .weak directives to arch/x86/lib/mem*_64.S instead of changing the
existing ENTRY macros to WEAK. This can lead to the assembly snippet

  .weak memcpy
  ...
  .globl memcpy

which will produce a STB_WEAK memcpy with GNU as but STB_GLOBAL memcpy
with LLVM's integrated assembler before LLVM 12. LLVM 12 (since
https://reviews.llvm.org/D90108) will error on such an overridden symbol
binding.

Commit

  ef1e03152c ("x86/asm: Make some functions local")

changed ENTRY in arch/x86/lib/memcpy_64.S to SYM_FUNC_START_LOCAL, which
was ineffective due to the preceding .weak directive.

Use the appropriate SYM_FUNC_START_WEAK instead.

Fixes: 393f203f5f ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions")
Fixes: ef1e03152c ("x86/asm: Make some functions local")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201103012358.168682-1-maskray@google.com
This commit is contained in:
Fangrui Song 2020-11-02 17:23:58 -08:00 committed by Borislav Petkov
parent 3cea11cd5e
commit 4d6ffa27b8
3 changed files with 3 additions and 9 deletions
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4
arch/x86/lib/memcpy_64.S
View File

@ -16,8 +16,6 @@
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
.weak memcpy
/*
* memcpy - Copy a memory block.
*
@ -30,7 +28,7 @@
* rax original destination
*/
SYM_FUNC_START_ALIAS(__memcpy)
SYM_FUNC_START_LOCAL(memcpy)
SYM_FUNC_START_WEAK(memcpy)
ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
"jmp memcpy_erms", X86_FEATURE_ERMS

4
arch/x86/lib/memmove_64.S
View File

@ -24,9 +24,7 @@
* Output:
* rax: dest
*/
.weak memmove
SYM_FUNC_START_ALIAS(memmove)
SYM_FUNC_START_WEAK(memmove)
SYM_FUNC_START(__memmove)
mov %rdi, %rax

4
arch/x86/lib/memset_64.S
View File

@ -6,8 +6,6 @@
#include <asm/alternative-asm.h>
#include <asm/export.h>
.weak memset
/*
* ISO C memset - set a memory block to a byte value. This function uses fast
* string to get better performance than the original function. The code is
@ -19,7 +17,7 @@
*
* rax original destination
*/
SYM_FUNC_START_ALIAS(memset)
SYM_FUNC_START_WEAK(memset)
SYM_FUNC_START(__memset)
/*
* Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended