Hi Dan, On Thu 29 Aug 2019 at 13:28, Dan Carpenter wrote:

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

Thanks so much for this, I was looking for some time at this and was half way to a much less elegant fix then yours.

Acked-by: Rui Miguel Silva rmfrfs@gmail.com

Cheers, Rui

---

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 010ae1e9c7fb..40680eaf3974 100644 --- a/drivers/staging/greybus/light.c +++ b/drivers/staging/greybus/light.c @@ -1098,21 +1098,21 @@ 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)