diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2016-11-22 11:49:32 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-11-23 22:57:20 +1100 |
| commit | 902e06eb86cd62753974c249bd1dedae2825b430 (patch) | |
| tree | d90f4d8be8f76eabed3ee9fae0cef5d13fc1077f /arch/powerpc/kernel | |
| parent | 6533b7c16ee5712041b4e324100550e02a9a5dda (diff) | |
powerpc/32: Change the stack protector canary value per task
Partially copied from commit df0698be14c66 ("ARM: stack protector:
change the canary value per task")
A new random value for the canary is stored in the task struct whenever
a new task is forked. This is meant to allow for different canary values
per task. On powerpc, GCC expects the canary value to be found in a global
variable called __stack_chk_guard. So this variable has to be updated
with the value stored in the task struct whenever a task switch occurs.
Because the variable GCC expects is global, this cannot work on SMP
unfortunately. So, on SMP, the same initial canary value is kept
throughout, making this feature a bit less effective although it is still
useful.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 6 |
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index caec7bf3b99a..5c860302efec 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -91,6 +91,9 @@ int main(void) DEFINE(TI_livepatch_sp, offsetof(struct thread_info, livepatch_sp)); #endif +#ifdef CONFIG_CC_STACKPROTECTOR + DEFINE(TSK_STACK_CANARY, offsetof(struct task_struct, stack_canary)); +#endif DEFINE(KSP, offsetof(struct thread_struct, ksp)); DEFINE(PT_REGS, offsetof(struct thread_struct, regs)); #ifdef CONFIG_BOOKE diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 3841d749a430..5742dbdbee46 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -674,7 +674,11 @@ BEGIN_FTR_SECTION mtspr SPRN_SPEFSCR,r0 /* restore SPEFSCR reg */ END_FTR_SECTION_IFSET(CPU_FTR_SPE) #endif /* CONFIG_SPE */ - +#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) + lwz r0,TSK_STACK_CANARY(r2) + lis r4,__stack_chk_guard@ha + stw r0,__stack_chk_guard@l(r4) +#endif lwz r0,_CCR(r1) mtcrf 0xFF,r0 /* r3-r12 are destroyed -- Cort */ |