Dmitry,
Any comments about this patch?
________________________________________
From: Estevam Fabio-R49496
Sent: Friday, August 03, 2012 8:41 AM
To: dmitry.torokhov@xxxxxxxxx
Cc: shawn.guo@xxxxxxxxxx; kernel@xxxxxxxxxxxxxx; aletes.xgr@xxxxxxxxx; rob.herring@xxxxxxxxxxx; linux-input@xxxxxxxxxxxxxxx; Estevam Fabio-R49496
Subject: [PATCH] Input: gpio_keys - fix NULL pointer dereference for dt case
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 <fabio.estevam@xxxxxxxxxxxxx>
Acked-by: Alexandre Pereira da Silva <aletes.xgr@xxxxxxxxx>
---
drivers/input/keyboard/gpio_keys.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 6ee68ec..620ef24 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -559,7 +559,6 @@ gpio_keys_get_devtree_pdata(struct device *dev)
struct gpio_keys_button *button;
int error;
int nbuttons;
- int i;
node = dev->of_node;
if (!node) {
@@ -580,9 +579,11 @@ gpio_keys_get_devtree_pdata(struct device *dev)
goto err_out;
}
+ pdata->buttons = (struct gpio_keys_button *) (pdata + 1);
+ pdata->nbuttons = nbuttons;
+
pdata->rep = !!of_get_property(node, "autorepeat", NULL);
- i = 0;
for_each_child_of_node(node, pp) {
enum of_gpio_flags flags;
@@ -592,8 +593,13 @@ gpio_keys_get_devtree_pdata(struct device *dev)
continue;
}
- button = &pdata->buttons[i++];
-
+ button = pdata->buttons;
+
+ if (!button) {
+ error = -ENOMEM;
+ goto err_free_pdata;
+ }
+
button->gpio = of_get_gpio_flags(pp, 0, &flags);
button->active_low = flags & OF_GPIO_ACTIVE_LOW;
@@ -614,6 +620,8 @@ gpio_keys_get_devtree_pdata(struct device *dev)
if (of_property_read_u32(pp, "debounce-interval",
&button->debounce_interval))
button->debounce_interval = 5;
+
+ button++;
}
if (pdata->nbuttons == 0) {
--
1.7.1
--
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