[PATCH AUTOSEL 4.14 283/371] staging: greybus: light: fix a couple double frees

Sasha Levin
2020-01-16T17:29:20Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 329101244f214952606359d254ae883b7109e1a5 ]

The problem is in gb_lights_request_handler(). If we get a request to
change the config then we release the light with gb_lights_light_release()
and re-allocated it. However, if the allocation fails part way through
then we call gb_lights_light_release() again. This can lead to a couple
different double frees where we haven't cleared out the original values:

gb_lights_light_v4l2_unregister(light);
...
kfree(light->channels);
kfree(light->name);

I also made a small change to how we set "light->channels_count = 0;".
The original code handled this part fine and did not cause a use after
free but it was sort of complicated to read.

Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
Link: https://lore.kernel.org/r/20190829122839.GA20116@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/greybus/light.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index 0f538b8c3a07..4e7575147775 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -1103,21 +1103,21 @@ static void gb_lights_channel_release(struct gb_channel *channel)
static void gb_lights_light_release(struct gb_light *light)
{
int i;
- int count;

light->ready = false;

- count = light->channels_count;
-
if (light->has_flash)
gb_lights_light_v4l2_unregister(light);
+ light->has_flash = false;

- for (i = 0; i < count; i++) {
+ for (i = 0; i < light->channels_count; i++)
gb_lights_channel_release(&light->channels[i]);
- light->channels_count--;
- }
+ light->channels_count = 0;
+
kfree(light->channels);
+ light->channels = NULL;
kfree(light->name);
+ light->name = NULL;
}

static void gb_lights_release(struct gb_lights *glights)
--
2.20.1