[PATCH 1/4] watchdog: imgpdc: Fix NULL pointer dereference on probe

Andrew Bresticker
2015-03-31T18:49:08Z

From: Naidu Tellapati <naidu.tellapati@imgtec.com>

pdc_wdt_probe() called pdc_wdt_stop() before watchdog_set_drvdata(),
resulting in the following NULL pointer dereference:

CPU 0 Unable to handle kernel paging request at virtual address 0000008c, epc == 8082a2b8, ra == 8082a914
Oops[#1]:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.0.0-rc5+ #102
task: 8f8c0000 ti: 8f89e000 task.ti: 8f89e000
$ 0 : 00000000 8082a914 00000000 dc8ba200
$ 4 : 8faf9418 80ac0000 8f9cdc10 00008012
$ 8 : 00000000 806e2350 00000001 8f001880
$12 : 8f89fd14 00000000 00000000 65646f4d
$16 : 8faf9418 8f9cdc10 8f001880 8f9cdc00
$20 : 00000000 80c20000 00000000 80bc0000
$24 : 00000002 00000000
$28 : 8f89e000 8f89fd00 00000000 8082a914
Hi : 0000006b
Lo : 00008013
epc : 8082a2b8 pdc_wdt_stop+0x1c/0x44
Not tainted
ra : 8082a914 pdc_wdt_probe+0x404/0x550
Status: 11000403 KERNEL EXL IE
Cause : 00800008
BadVA : 0000008c
PrId : 0001a120 (MIPS interAptiv (multi))

Fix it by moving the call to pdc_wdt_stop() after we've set drvdata.

Signed-off-by: Naidu Tellapati <naidu.tellapati@imgtec.com>
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
---
drivers/watchdog/imgpdc_wdt.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/imgpdc_wdt.c b/drivers/watchdog/imgpdc_wdt.c
index c8def68..c4151cd 100644
--- a/drivers/watchdog/imgpdc_wdt.c
+++ b/drivers/watchdog/imgpdc_wdt.c
@@ -199,8 +199,6 @@ static int pdc_wdt_probe(struct platform_device *pdev)
"Initial timeout out of range! setting max timeout\n");
}

- pdc_wdt_stop(&pdc_wdt->wdt_dev);
-
/* Find what caused the last reset */
val = readl(pdc_wdt->base + PDC_WDT_TICKLE1);
val = (val & PDC_WDT_TICKLE_STATUS_MASK) >> PDC_WDT_TICKLE_STATUS_SHIFT;
@@ -234,6 +232,8 @@ static int pdc_wdt_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, pdc_wdt);
watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);

+ pdc_wdt_stop(&pdc_wdt->wdt_dev);
+
ret = watchdog_register_device(&pdc_wdt->wdt_dev);
if (ret)
goto disable_wdt_clk;
--
2.2.0.rc0.207.ga3a616c