Re: [PATCH] Input: gpio_keys - fix NULL pointer dereference for dt case

On Mon, Aug 06, 2012 at 02:20:27PM +0530, Shubhrajyoti wrote:

On Friday 03 August 2012 07:11 PM, Fabio Estevam wrote:

quoted

Commit 30161f6b2e7d1 (Input: gpio_keys - clean up device tree parser) 
introduced the following kernel crash for a dt based kernel:
..
Unable to handle kernel NULL pointer dereference at virtual address 00000004
pgd = 80004000
[00000004] *pgd=00000000
Internal error: Oops: 805 [#1] ARM
Modules linked in:
CPU: 0    Not tainted  (3.5.0-next-20120802+ #1366)
PC is at gpio_keys_probe+0x154/0x8c0
LR is at of_gpiochip_find_and_xlate+0x54/0x70
pc : [<803ddbac>]    lr : [<801ed2f4>]    psr: 60000013
sp : 9f851df8  ip : 00000002  fp : 9f851e5c
r10: 9f873d00  r9 : 00000001  r8 : 9fa2f900
r7 : 809c0920  r6 : 9f873d08  r5 : 00000000  r4 : 809c09d4
r3 : 805af10c  r2 : 000000c0  r1 : 9f851db4  r0 : 000000d5
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c5387d  Table: 90004019  DAC: 00000015
Process swapper (pid: 1, stack limit = 0x9f8502e8)
Stack: (0x9f851df8 to 0x9f852000)
....

The reason for the crash was due to 'button = &pdata->buttons[i++];' 
returning a NULL pointer, and then 'button' was accessed afterwards 
without checking for NULL.

Fix this by correctly assigning 'pdata->buttons' and also add a NULL 
pointer check for 'button' pointer.

Signed-off-by: Fabio Estevam <redacted>
Acked-by: Alexandre Pereira da Silva <redacted>

Should we cc stable?

No, because it hasn't hit mainline.

Thanks.

-- 
Dmitry