[PATCH AUTOSEL 4.9 45/87] leds: lp55xx: fix null deref on firmware load failure

Sasha Levin
2019-03-27T18:42:35Z

From: Michal Kazior <michal@plume.com>

[ Upstream commit 5ddb0869bfc1bca6cfc592c74c64a026f936638c ]

I've stumbled upon a kernel crash and the logs
pointed me towards the lp5562 driver:

> <4>[306013.841294] lp5562 0-0030: Direct firmware load for lp5562 failed with error -2
> <4>[306013.894990] lp5562 0-0030: Falling back to user helper
> ...
> <3>[306073.924886] lp5562 0-0030: firmware request failed
> <1>[306073.939456] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> <4>[306074.251011] PC is at _raw_spin_lock+0x1c/0x58
> <4>[306074.255539] LR is at release_firmware+0x6c/0x138
> ...

After taking a look I noticed firmware_release()
could be called with either NULL or a dangling
pointer.

Fixes: 10c06d178df11 ("leds-lp55xx: support firmware interface")
Signed-off-by: Michal Kazior <michal@plume.com>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/leds/leds-lp55xx-common.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
index 5377f22ff994..e2655953667c 100644
--- a/drivers/leds/leds-lp55xx-common.c
+++ b/drivers/leds/leds-lp55xx-common.c
@@ -201,7 +201,7 @@ static void lp55xx_firmware_loaded(const struct firmware *fw, void *context)

if (!fw) {
dev_err(dev, "firmware request failed\n");
- goto out;
+ return;
}

/* handling firmware data is chip dependent */
@@ -214,9 +214,9 @@ static void lp55xx_firmware_loaded(const struct firmware *fw, void *context)

mutex_unlock(&chip->lock);

-out:
/* firmware should be released for other channel use */
release_firmware(chip->fw);
+ chip->fw = NULL;
}

static int lp55xx_request_firmware(struct lp55xx_chip *chip)
--
2.19.1