[PATCH v2] staging: greybus: lights: avoid NULL deref

[Chaitanya Mishra <chaitanyamishra.ai@gmail.com>]

gb_lights_light_config() stores channel_count before allocating the
channels array. If kcalloc() fails, gb_lights_release() iterates the
non-zero count and dereferences light->channels, which is NULL.

Allocate channels first and only then publish channels_count so the
cleanup path can't walk a NULL pointer.

Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
Signed-off-by: Chaitanya Mishra <chaitanyamishra.ai@gmail.com>
---
 drivers/staging/greybus/light.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index e509fdc715db..38c233a706c4 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -1008,14 +1008,18 @@ static int gb_lights_light_config(struct gb_lights *glights, u8 id)
 	if (!strlen(conf.name))
 		return -EINVAL;
 
-	light->channels_count = conf.channel_count;
 	light->name = kstrndup(conf.name, NAMES_MAX, GFP_KERNEL);
 	if (!light->name)
 		return -ENOMEM;
-	light->channels = kcalloc(light->channels_count,
+	light->channels = kcalloc(conf.channel_count,
 				  sizeof(struct gb_channel), GFP_KERNEL);
 	if (!light->channels)
 		return -ENOMEM;
+	/*
+	 * Publish channels_count only after channels allocation so cleanup
+	 * doesn't walk a NULL channels pointer on allocation failure.
+	 */
+	light->channels_count = conf.channel_count;
 
 	/* First we collect all the configurations for all channels */
 	for (i = 0; i < light->channels_count; i++) {
-- 
2.50.1 (Apple Git-155)