[PATCH] powerpc/crash: Rearrange loop condition to avoid out of bounds array access

[PATCH] powerpc/crash: Rearrange loop condition to avoid out of bounds array access

[Suraj Jitindar Singh]

The array crash_shutdown_handles[] has size CRASH_HANDLER_MAX, thus when
we loop over the elements of the list we check crash_shutdown_handles[i]
&& i < CRASH_HANDLER_MAX. However this means that when we increment i to
CRASH_HANDLER_MAX we will perform an out of bound array access checking
the first condition before exiting on the second condition.

To avoid the out of bounds access, simply reorder the loop conditions.

Fixes Coverity bug #128232

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/kernel/crash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/crash.c b/arch/powerpc/kernel/crash.c
index 888bdf1..47b63de 100644
--- a/arch/powerpc/kernel/crash.c
+++ b/arch/powerpc/kernel/crash.c
@@ -351,7 +351,7 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	old_handler = __debugger_fault_handler;
 	__debugger_fault_handler = handle_fault;
 	crash_shutdown_cpu = smp_processor_id();
-	for (i = 0; crash_shutdown_handles[i] && i < CRASH_HANDLER_MAX; i++) {
+	for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) {
 		if (setjmp(crash_shutdown_buf) == 0) {
 			/*
 			 * Insert syncs and delay to ensure
-- 
2.5.5

Re: [PATCH] powerpc/crash: Rearrange loop condition to avoid out of bounds array access

[Andrew Donnellan]

On 11/07/16 14:17, Suraj Jitindar Singh wrote:
> The array crash_shutdown_handles[] has size CRASH_HANDLER_MAX, thus when
> we loop over the elements of the list we check crash_shutdown_handles[i]
> && i < CRASH_HANDLER_MAX. However this means that when we increment i to
> CRASH_HANDLER_MAX we will perform an out of bound array access checking
> the first condition before exiting on the second condition.
>
> To avoid the out of bounds access, simply reorder the loop conditions.
>
> Fixes Coverity bug #128232
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Fixes: 1d1451655bad ("powerpc: Add array bounds checking to 
crash_shutdown_handlers")
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

Re: powerpc/crash: Rearrange loop condition to avoid out of bounds array access

[Michael Ellerman]

On Mon, 2016-11-07 at 04:17:31 UTC, Suraj Jitindar Singh wrote:
> The array crash_shutdown_handles[] has size CRASH_HANDLER_MAX, thus when
> we loop over the elements of the list we check crash_shutdown_handles[i]
> && i < CRASH_HANDLER_MAX. However this means that when we increment i to
> CRASH_HANDLER_MAX we will perform an out of bound array access checking
> the first condition before exiting on the second condition.
> 
> To avoid the out of bounds access, simply reorder the loop conditions.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/a7d6392866e9777cb287ad194c

cheers