From: Alan Stern <stern@rowland.harvard.edu> To: Greg KH <greg@kroah.com> Cc: Tomoki Sekiyama <tomoki.sekiyama@gmail.com>, <andreyknvl@google.com>, <chunfeng.yun@mediatek.com>, USB list <linux-usb@vger.kernel.org>, <syzkaller-bugs@googlegroups.com> Subject: [PATCH] USB: yurex: Don't retry on unexpected errors Date: Tue, 17 Sep 2019 12:47:23 -0400 (EDT) Message-ID: <Pine.LNX.4.44L0.1909171245410.1590-100000@iolanthe.rowland.org> (raw) In-Reply-To: <0000000000001603470592b13bfc@google.com> According to Greg KH, it has been generally agreed that when a USB driver encounters an unknown error (or one it can't handle directly), it should just give up instead of going into a potentially infinite retry loop. The three codes -EPROTO, -EILSEQ, and -ETIME fall into this category. They can be caused by bus errors such as packet loss or corruption, attempting to communicate with a disconnected device, or by malicious firmware. Nowadays the extent of packet loss or corruption is negligible, so it should be safe for a driver to give up whenever one of these errors occurs. Although the yurex driver handles -EILSEQ errors in this way, it doesn't do the same for -EPROTO (as discovered by the syzbot fuzzer) or other unrecognized errors. This patch adjusts the driver so that it doesn't log an error message for -EPROTO or -ETIME, and it doesn't retry after any errors. Reported-and-tested-by: syzbot+b24d736f18a1541ad550@syzkaller.appspotmail.com Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Tomoki Sekiyama <tomoki.sekiyama@gmail.com> CC: <stable@vger.kernel.org> --- [as1918] drivers/usb/misc/yurex.c | 7 ++++--- 1 file changed, 4 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 +141,13 @@ static void yurex_interrupt(struct urb * case -ENOENT: case -ESHUTDOWN: case -EILSEQ: - /* The device is terminated, clean up */ + case -EPROTO: + case -ETIME: return; default: dev_err(&dev->interface->dev, "%s - unknown status received: %d\n", __func__, status); - goto exit; + return; } /* handle received message */ @@ -177,7 +179,6 @@ 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",
prev parent reply index 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 2019-09-16 20:13 ` syzbot 2019-09-17 16:47 ` Alan Stern [this message]
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