[Linux-kernel-mentees] [PATCH V2] media: usb: technisat-usb2: fix buffer overflow

Phong Tran tranmanphong at gmail.com
Wed Jul 3 02:14:44 UTC 2019


The buffer will be overflow in case of the while loop can not break.
Add the checking buffer condition in while loop for avoiding
overlooping index.

This issue was reported by syzbot

Reported-by: syzbot+eaaaf38a95427be88f4b at syzkaller.appspotmail.com

Tested-by:
https://groups.google.com/d/msg/syzkaller-bugs/CySBCKuUOOs/t3PvVheSAAAJ

Signed-off-by: Phong Tran <tranmanphong at gmail.com>
---
Change Log:
 * V2: add IR_MAX_BUFFER_INDEX and adjust the while loop condition as comments
---
 drivers/media/usb/dvb-usb/technisat-usb2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/technisat-usb2.c b/drivers/media/usb/dvb-usb/technisat-usb2.c
index c659e18b358b..cdabff97c1ea 100644
--- a/drivers/media/usb/dvb-usb/technisat-usb2.c
+++ b/drivers/media/usb/dvb-usb/technisat-usb2.c
@@ -49,6 +49,7 @@ MODULE_PARM_DESC(disable_led_control,
 		"disable LED control of the device (default: 0 - LED control is active).");
 
 /* device private data */
+#define IR_MAX_BUFFER_INDEX	63
 struct technisat_usb2_state {
 	struct dvb_usb_device *dev;
 	struct delayed_work green_led_work;
@@ -56,7 +57,7 @@ struct technisat_usb2_state {
 
 	u16 last_scan_code;
 
-	u8 buf[64];
+	u8 buf[IR_MAX_BUFFER_INDEX + 1];
 };
 
 /* debug print helpers */
@@ -655,7 +656,7 @@ static int technisat_usb2_get_ir(struct dvb_usb_device *d)
 #endif
 
 	ev.pulse = 0;
-	while (1) {
+	while (b <= (buf + IR_MAX_BUFFER_INDEX)) {
 		ev.pulse = !ev.pulse;
 		ev.duration = (*b * FIRMWARE_CLOCK_DIVISOR * FIRMWARE_CLOCK_TICK) / 1000;
 		ir_raw_event_store(d->rc_dev, &ev);
-- 
2.11.0



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