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* KMSAN: uninit-value in digitv_rc_query
@ 2019-11-08 17:04 syzbot
  2019-12-03  0:41 ` [PATCH] media: dvb: check return value digitv_ctrl_msg Phong Tran
  0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2019-11-08 17:04 UTC (permalink / raw)
  To: glider, linux-kernel, linux-media, mchehab, syzkaller-bugs

Hello,

syzbot found the following crash on:

HEAD commit:    1e76a3e5 kmsan: replace __GFP_NO_KMSAN_SHADOW with kmsan_i..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16860a63600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f03c659d0830ab8d
dashboard link: https://syzkaller.appspot.com/bug?extid=6bf9606ee955b646c0e1
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12c1101b600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15db3cfd600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6bf9606ee955b646c0e1@syzkaller.appspotmail.com

dvb-usb: schedule remote query interval to 1000 msecs.
dvb-usb: Nebula Electronics uDigiTV DVB-T USB2.0) successfully initialized  
and connected.
dvb-usb: bulk message failed: -22 (7/0)
dvb-usb: bulk message failed: -22 (7/0)
dvb-usb: bulk message failed: -22 (7/-30591)
dvb-usb: bulk message failed: -22 (7/0)
=====================================================
BUG: KMSAN: uninit-value in legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
CPU: 1 PID: 3844 Comm: kworker/1:2 Not tainted 5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events legacy_dvb_usb_read_remote_control
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
  kmsan_report+0x13a/0x2b0 mm/kmsan/kmsan_report.c:108
  __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
  digitv_rc_query+0x76a/0x890 drivers/media/usb/dvb-usb/digitv.c:259
  legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
  process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
  worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
  kthread+0x4b5/0x4f0 kernel/kthread.c:256
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Local variable description: ----key@digitv_rc_query
Variable was created at:
  digitv_rc_query+0x78/0x890 drivers/media/usb/dvb-usb/digitv.c:234
  legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
=====================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 3844 Comm: kworker/1:2 Tainted: G    B             5.3.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events legacy_dvb_usb_read_remote_control
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
  panic+0x3c9/0xc1e kernel/panic.c:219
  kmsan_report+0x2a2/0x2b0 mm/kmsan/kmsan_report.c:131
  __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
  digitv_rc_query+0x76a/0x890 drivers/media/usb/dvb-usb/digitv.c:259
  legacy_dvb_usb_read_remote_control+0x106/0x790  
drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
  process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
  worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
  kthread+0x4b5/0x4f0 kernel/kthread.c:256
  ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [PATCH] media: dvb: check return value digitv_ctrl_msg
  2019-11-08 17:04 KMSAN: uninit-value in digitv_rc_query syzbot
@ 2019-12-03  0:41 ` Phong Tran
  0 siblings, 0 replies; 2+ messages in thread
From: Phong Tran @ 2019-12-03  0:41 UTC (permalink / raw)
  To: mchehab, gregkh, allison, tglx, syzbot+6bf9606ee955b646c0e1
  Cc: linux-media, linux-kernel, glider, syzkaller-bugs, Phong Tran

For fixing syzbot "KMSAN: uninit-value in digitv_rc_query"

In scenario testing for syzbot, failure reading from
digitv_ctrl_msg() [1].

Eg:
[   91.846657][ T3844] dvb-usb: bulk message failed: -22 (7/0)

digitv_rc_query() always return 0. But in this case a wrong thing happens.

Reported-by: syzbot+6bf9606ee955b646c0e1@syzkaller.appspotmail.com
Tested-by: syzbot+6bf9606ee955b646c0e1@syzkaller.appspotmail.com

[1]: https://syzkaller.appspot.com/text?tag=CrashLog&x=16860a63600000
[2]: https://groups.google.com/d/msg/syzkaller-bugs/-TXIJAZ0J9Q/T4PEUQoeAQAJ

Signed-off-by: Phong Tran <tranmanphong@gmail.com>
---
 drivers/media/usb/dvb-usb/digitv.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/digitv.c b/drivers/media/usb/dvb-usb/digitv.c
index dd5bb230cec1..61bc8945e6b9 100644
--- a/drivers/media/usb/dvb-usb/digitv.c
+++ b/drivers/media/usb/dvb-usb/digitv.c
@@ -231,17 +231,21 @@ static struct rc_map_table rc_map_digitv_table[] = {
 static int digitv_rc_query(struct dvb_usb_device *d, u32 *event, int *state)
 {
 	int i;
-	u8 key[5];
+	u8 key[5] = { 0 };
 	u8 b[4] = { 0 };
+	int ret;
 
 	*event = 0;
 	*state = REMOTE_NO_KEY_PRESSED;
 
-	digitv_ctrl_msg(d,USB_READ_REMOTE,0,NULL,0,&key[1],4);
-
+	ret = digitv_ctrl_msg(d, USB_READ_REMOTE, 0, NULL, 0, &key[1], 4);
+	if (ret < 0)
+		return ret;
 	/* Tell the device we've read the remote. Not sure how necessary
 	   this is, but the Nebula SDK does it. */
-	digitv_ctrl_msg(d,USB_WRITE_REMOTE,0,b,4,NULL,0);
+	ret = digitv_ctrl_msg(d, USB_WRITE_REMOTE, 0, b, 4, NULL, 0);
+	if (ret < 0)
+		return ret;
 
 	/* if something is inside the buffer, simulate key press */
 	if (key[1] != 0)
-- 
2.20.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2019-11-08 17:04 KMSAN: uninit-value in digitv_rc_query syzbot
2019-12-03  0:41 ` [PATCH] media: dvb: check return value digitv_ctrl_msg Phong Tran

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