[PATCH] arch: tile: fix null pointer dereference on pt_regs pointer

[PATCH] arch: tile: fix null pointer dereference on pt_regs pointer

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Cppcheck reports the following issue:
[arch/tile/kernel/stack.c:116]: (error) Possible null
  pointer dereference: p

In this case, on reporting on an odd fault, p is set to NULL
and immediately afterwords p is dereferenced iff
!kbt->profile is false.  Rather than doing this check just
return NULL rather than falling through to the potential
null pointer dereference (since the original intentional
outcome would be to return NULL anyhow) for this odd fault
case.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 arch/tile/kernel/stack.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c
index 7ff5afd..2d55c04 100644
--- a/arch/tile/kernel/stack.c
+++ b/arch/tile/kernel/stack.c
@@ -111,7 +111,7 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
 	} else if (kbt->verbose) {
 		pr_err("  (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
 		       p->pc, p->sp, p->ex1);
-		p = NULL;
+		return NULL;
 	}
 	if (!kbt->profile || ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) == 0)
 		return p;
-- 
2.1.4

Re: [PATCH] arch: tile: fix null pointer dereference on pt_regs pointer

[Chris Metcalf]

On 3/1/2015 3:12 PM, Colin King wrote:
> From: Colin Ian King<colin.king@canonical.com>
>
> Cppcheck reports the following issue:
> [arch/tile/kernel/stack.c:116]: (error) Possible null
>    pointer dereference: p
>
> In this case, on reporting on an odd fault, p is set to NULL
> and immediately afterwords p is dereferenced iff
> !kbt->profile is false.  Rather than doing this check just
> return NULL rather than falling through to the potential
> null pointer dereference (since the original intentional
> outcome would be to return NULL anyhow) for this odd fault
> case.
>
> Signed-off-by: Colin Ian King<colin.king@canonical.com>
> ---
>   arch/tile/kernel/stack.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Thanks!  I tweaked this a bit and took it into the tile tree.

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com