diff options
| author | Michael Neuling <mikey@neuling.org> | 2014-01-21 09:52:17 +1100 |
|---|---|---|
| committer | Eli Qiao <taget@linux.vnet.ibm.com> | 2014-01-22 10:26:21 +0800 |
| commit | b47c7d6f260e8db1eef1c6441ed368f3526d3760 (patch) | |
| tree | 8848ed8785b26f93bbb19e54383da280564f8b69 | |
| parent | bf3e78ac9174ed22bed9df94c41f347885f20dcd (diff) | |
| download | powerkvm-b47c7d6f260e8db1eef1c6441ed368f3526d3760.tar.gz | |
powerpc: Fix bad stack check in exception entry
In EXCEPTION_PROLOG_COMMON() we check to see if the stack pointer (r1)
is valid when coming from the kernel. If it's not valid, we die but
with a nice oops message.
Currently we allocate a stack frame (subtract INT_FRAME_SIZE) before we
check to see if the stack pointer is negative. Unfortunately, this
won't detect a bad stack where r1 is less than INT_FRAME_SIZE.
This patch fixes the check to compare the modified r1 with
-INT_FRAME_SIZE. With this, bad kernel stack pointers (including NULL
pointers) are correctly detected again.
Kudos to Paulus for finding this.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
| -rw-r--r-- | arch/powerpc/include/asm/exception-64s.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index 8f3947fa3dfc5a..aa0e5d68e8b726 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -284,7 +284,7 @@ do_kvm_##n: \ subi r1,r1,INT_FRAME_SIZE; /* alloc frame on kernel stack */ \ beq- 1f; \ ld r1,PACAKSAVE(r13); /* kernel stack to use */ \ -1: cmpdi cr1,r1,0; /* check if r1 is in userspace */ \ +1: cmpdi cr1,r1,-INT_FRAME_SIZE; /* check if r1 is in userspace */ \ blt+ cr1,3f; /* abort if it is */ \ li r1,(n); /* will be reloaded later */ \ sth r1,PACA_TRAP_SAVE(r13); \ |