3.5.7.29 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Michael Neuling <[email protected]> commit 90ff5d688e61f49f23545ffab6228bd7e87e6dc7 upstream. 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 <[email protected]> Signed-off-by: Benjamin Herrenschmidt <[email protected]> Signed-off-by: Luis Henriques <[email protected]> --- arch/powerpc/include/asm/exception-64s.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index 6afb13a..241d2f3 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -163,7 +163,7 @@ 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); \ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
