From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Rui Miguel Silva <rui.silva@linaro.org>,
	Chaitanya Mishra <chaitanyamishra.ai@gmail.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 460/641] staging: greybus: lights: avoid NULL deref
Date: Tue, 24 Feb 2026 17:23:06 -0800
Message-ID: <20260225012359.662197014@linuxfoundation.org>
In-Reply-To: <20260225012348.915798704@linuxfoundation.org>
References: <20260225012348.915798704@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chaitanya Mishra <chaitanyamishra.ai@gmail.com>

[ Upstream commit efcffd9a6ad8d190651498d5eda53bfc7cf683a7 ]

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")
Link: https://lore.kernel.org/all/20260108103700.15384-1-chaitanyamishra.ai@gmail.com/
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Chaitanya Mishra <chaitanyamishra.ai@gmail.com>
Link: https://patch.msgid.link/20260108151254.81553-1-chaitanyamishra.ai@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 e509fdc715dbb..38c233a706c48 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++) {
-- 
2.51.0