On 3/2/24 3:59 AM, Dan Carpenter wrote:
On Fri, Mar 01, 2024 at 02:04:24PM -0500, Mikhail Lobanov wrote:
Dereference of null pointer in the __gb_lights_flash_brightness_set function.
Assigning the channel the result of executing the get_channel_from_mode function
without checking for NULL may result in an error.
get_channel_from_mode() can only return NULL when light->channels_count
is zero.
Although get_channel_from_mode() seems buggy to me. If it can't
find the correct mode, it just returns the last channel. So potentially
it should be made to return NULL.
I agree with you. This looks quite wrong to me, and I
like your fix, *except* there is also no need to check
whether the channel pointer is null inside the loop.
It's the address of an object, and will always be non-null.
static struct gb_channel *
get_channel_from_mode(struct gb_light *light, u32 mode)
{
struct gb_channel *channel;
u32 i;
for (i = 0; i < light->channels_count; i++) {
channel = &light->channels[i];
if (channel->mode == mode)
return channel;
}
return NULL;
}
Rui, could you please confirm what Dan says (and his
proposed change) was your intention?
If so (and assuming you also fix the check for a null
channel pointer inside the loop):
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
-Alex
diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index d62f97249aca..acd435f5d25d 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -95,15 +95,15 @@ static struct led_classdev *get_channel_cdev(struct gb_channel *channel)
static struct gb_channel *get_channel_from_mode(struct gb_light *light,
u32 mode)
{
- struct gb_channel *channel = NULL;
+ struct gb_channel *channel;
int i;
for (i = 0; i < light->channels_count; i++) {
channel = &light->channels[i];
if (channel && channel->mode == mode)
- break;
+ return channel;
}
- return channel;
+ return NULL;
}
static int __gb_lights_flash_intensity_set(struct gb_channel *channel,
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