linux-kernel - [PATCH 5.16 0245/1039] media: uvcvideo: Avoid invalid memory access

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Date:   Mon, 24 Jan 2022 19:33:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ricardo Ribalda <ribalda@...omium.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0245/1039] media: uvcvideo: Avoid invalid memory access

From: Ricardo Ribalda <ribalda@...omium.org>

[ Upstream commit f0577b1b6394f954903fcc67e12fe9e7001dafd6 ]

If mappings points to an invalid memory, we will be invalid accessing
it. Solve it by initializing the value of the variable mapping and by
changing the order in the conditional statement (to avoid accessing
mapping->id if not needed).

Fix:
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN NOPTI

Fixes: 6350d6a4ed487 ("media: uvcvideo: Set error_idx during ctrl_commit errors")
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 30bfe9069a1fb..9a25d60292558 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1638,7 +1638,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
 				  struct v4l2_ext_controls *ctrls,
 				  struct uvc_control *uvc_control)
 {
-	struct uvc_control_mapping *mapping;
+	struct uvc_control_mapping *mapping = NULL;
 	struct uvc_control *ctrl_found;
 	unsigned int i;
 
-- 
2.34.1