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From: Alan Stern <stern@rowland.harvard.edu>
To: syzbot <syzbot+b24d736f18a1541ad550@syzkaller.appspotmail.com>
Cc: andreyknvl@google.com, <balbi@kernel.org>,
	<chunfeng.yun@mediatek.com>, <gregkh@linuxfoundation.org>,
	<linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>,
	<syzkaller-bugs@googlegroups.com>
Subject: Re: INFO: rcu detected stall in dummy_timer
Date: Mon, 16 Sep 2019 15:53:05 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1909161551020.1489-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <0000000000004fb020059274a5ff@google.com>

On Fri, 13 Sep 2019, syzbot wrote:

> syzbot has found a reproducer for the following crash on:
> 
> HEAD commit:    f0df5c1b usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=1146550d600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5
> dashboard link: https://syzkaller.appspot.com/bug?extid=b24d736f18a1541ad550
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11203fa5600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=162cd335600000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b24d736f18a1541ad550@syzkaller.appspotmail.com
> 
> yurex 3-1:0.101: yurex_interrupt - unknown status received: -71
> yurex 5-1:0.101: yurex_interrupt - unknown status received: -71
> yurex 6-1:0.101: yurex_interrupt - unknown status received: -71

Let's see if preventing blind resubmissions fixes the problem.

Alan Stern

#syz test: https://github.com/google/kasan.git f0df5c1b

 drivers/usb/misc/yurex.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: usb-devel/drivers/usb/misc/yurex.c
===================================================================
--- usb-devel.orig/drivers/usb/misc/yurex.c
+++ usb-devel/drivers/usb/misc/yurex.c
@@ -132,6 +132,7 @@ static void yurex_interrupt(struct urb *
 	switch (status) {
 	case 0: /*success*/
 		break;
+	/* The device is terminated or messed up, give up */
 	case -EOVERFLOW:
 		dev_err(&dev->interface->dev,
 			"%s - overflow with length %d, actual length is %d\n",
@@ -140,12 +141,12 @@ static void yurex_interrupt(struct urb *
 	case -ENOENT:
 	case -ESHUTDOWN:
 	case -EILSEQ:
-		/* The device is terminated, clean up */
+	case -EPROTO:
 		return;
 	default:
 		dev_err(&dev->interface->dev,
 			"%s - unknown status received: %d\n", __func__, status);
-		goto exit;
+		return;
 	}
 
 	/* handle received message */
@@ -177,7 +178,6 @@ static void yurex_interrupt(struct urb *
 		break;
 	}
 
-exit:
 	retval = usb_submit_urb(dev->urb, GFP_ATOMIC);
 	if (retval) {
 		dev_err(&dev->interface->dev, "%s - usb_submit_urb failed: %d\n",


  parent reply	other threads:[~2019-09-16 19:53 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 13:18 INFO: rcu detected stall in dummy_timer syzbot
2019-09-13 19:56 ` syzbot
2019-09-13 20:35   ` Alan Stern
2019-09-16 15:29     ` Andrey Konovalov
2019-09-16 16:32       ` Alan Stern
2019-09-16 18:59         ` Greg Kroah-Hartman
2019-09-16 19:48           ` Alan Stern
2019-09-18 11:22         ` Andrey Konovalov
2019-09-18 14:16           ` Alan Stern
2019-09-16 19:53   ` Alan Stern [this message]
2019-09-16 20:13     ` syzbot
2019-09-17 16:47       ` [PATCH] USB: yurex: Don't retry on unexpected errors Alan Stern

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