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PLT avoidance for __stack_chk_fail [BZ #7065] 

Add a hidden __stack_chk_fail_local alias to libc.so,
and make sure that on targets which use __stack_chk_fail,
this does not introduce a local PLT reference into libc.so.
This commit is contained in:
Nick Alcock 2016-12-26 10:08:57 +01:00 committed by Florian Weimer
parent 66a704c43c
commit 524a8ef2ad
4 changed files with 34 additions and 0 deletions
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14
ChangeLog
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@ -1,3 +1,17 @@
2016-12-26 Nick Alcock <nick.alcock@oracle.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Florian Weimer <fweimer@redhat.com>
[BZ #7065]
PLT avoidance for __stack_chk_fail*.
* debug/Makefile (CFLAGS-stack_chk_fail.c)
(CFLAGS-stack_chk_fail_local.c): Build without stack protector.
* debug/stack_chk_fail.c (__stack_chk_fail): Add
__stack_chk_fail_local alias.
* sysdeps/generic/symbol-hacks.h [IS_IN (libc)]
(__stack_chk_fail): Turn into hidden reference to
__stack_chk_fail_local.
2016-12-26 Nick Alcock <nick.alcock@oracle.com>
[BZ #7065]

6
debug/Makefile
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@ -53,6 +53,12 @@ routines = backtrace backtracesyms backtracesymsfd noophooks \
$(static-only-routines)
static-only-routines := warning-nop stack_chk_fail_local
# Building the stack-protector failure routines with stack protection
# makes no sense.
CFLAGS-stack_chk_fail.c = $(no-stack-protector)
CFLAGS-stack_chk_fail_local.c = $(no-stack-protector)
CFLAGS-backtrace.c = -fno-omit-frame-pointer
CFLAGS-sprintf_chk.c = $(libio-mtsafe)
CFLAGS-snprintf_chk.c = $(libio-mtsafe)

2
debug/stack_chk_fail.c
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@ -27,3 +27,5 @@ __stack_chk_fail (void)
{
__fortify_fail ("stack smashing detected");
}
strong_alias (__stack_chk_fail, __stack_chk_fail_local)

12
sysdeps/generic/symbol-hacks.h
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@ -4,4 +4,16 @@
asm ("memmove = __GI_memmove");
asm ("memset = __GI_memset");
asm ("memcpy = __GI_memcpy");
/* Some targets do not use __stack_chk_fail_local. In libc.so,
redirect __stack_chk_fail to a hidden reference
__stack_chk_fail_local, to avoid the PLT reference.
__stack_chk_fail itself is a global symbol, exported from libc.so,
and cannot be made hidden. */
# if IS_IN (libc) && defined SHARED && \
defined STACK_PROTECTOR_LEVEL && STACK_PROTECTOR_LEVEL > 0
asm (".hidden __stack_chk_fail_local\n"
"__stack_chk_fail = __stack_chk_fail_local");
# endif
#endif