linux-kernel - [PATCH v3] media: gspca: UBSAN: shift-out-of-bounds in set

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Date:   Thu, 24 Aug 2023 14:27:31 +0530
From:   coolrrsh@...il.com
To:     hverkuil@...all.nl, mchehab@...nel.org, slark_xiao@....com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        Rajeshwar R Shinde <coolrrsh@...il.com>,
        syzbot+e27f3dbdab04e43b9f73@...kaller.appspotmail.com
Subject: [PATCH v3] media: gspca: UBSAN: shift-out-of-bounds in set_flicker

From: Rajeshwar R Shinde <coolrrsh@...il.com>

Syzkaller reported the following issue:
							
UBSAN: shift-out-of-bounds in drivers/media/usb/gspca/cpia1.c:1031:27 
shift exponent 245 is too large for 32-bit type 'int'
						
When the value of the variable "sd->params.exposure.gain" exceeds the 
number of bits in an int, a shift-out-of-bounds error occurs. The error is 
generated when the variable "currentexp" is left-shifted by more than 31 
bits. In order to confirm the range is valid, the conditional expression 
was added.
				
Reported-by: syzbot+e27f3dbdab04e43b9f73@...kaller.appspotmail.com
Closes: https://lore.kernel.org/all/20230818164522.12806-1-coolrrsh@gmail.com
Link: https://syzkaller.appspot.com/bug?extid=e27f3dbdab04e43b9f73
Signed-off-by: Rajeshwar R Shinde <coolrrsh@...il.com>							
---
v1->v2			
Changed the patch
v2->v3				
Changed the commit message	
---
 drivers/media/usb/gspca/cpia1.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/media/usb/gspca/cpia1.c b/drivers/media/usb/gspca/cpia1.c
index 46ed95483e22..dafc522d5e7b 100644
--- a/drivers/media/usb/gspca/cpia1.c
+++ b/drivers/media/usb/gspca/cpia1.c
@@ -1028,6 +1028,8 @@ static int set_flicker(struct gspca_dev *gspca_dev, int on, int apply)
 			sd->params.exposure.expMode = 2;
 			sd->exposure_status = EXPOSURE_NORMAL;
 		}
+		if (sd->params.exposure.gain > 31)
+			return -1;
 		currentexp = currentexp << sd->params.exposure.gain;
 		sd->params.exposure.gain = 0;
 		/* round down current exposure to nearest value */
-- 
2.25.1