diff options
authorAlan Stern <stern@rowland.harvard.edu>2020-05-01 16:07:28 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-05-27 17:37:34 +0200
commit661595bc360a62c337215353118d5564c234f3fa (patch)
parente5645ec7f7152e44a64b726025b86aef5fd0907c (diff)
USB: core: Fix misleading driver bug report
[ Upstream commit ac854131d9844f79e2fdcef67a7707227538d78a ] The syzbot fuzzer found a race between URB submission to endpoint 0 and device reset. Namely, during the reset we call usb_ep0_reinit() because the characteristics of ep0 may have changed (if the reset follows a firmware update, for example). While usb_ep0_reinit() is running there is a brief period during which the pointers stored in udev->ep_in[0] and udev->ep_out[0] are set to NULL, and if an URB is submitted to ep0 during that period, usb_urb_ep_type_check() will report it as a driver bug. In the absence of those pointers, the routine thinks that the endpoint doesn't exist. The log message looks like this: ------------[ cut here ]------------ usb 2-1: BOGUS urb xfer, pipe 2 != type 2 WARNING: CPU: 0 PID: 9241 at drivers/usb/core/urb.c:478 usb_submit_urb+0x1188/0x1460 drivers/usb/core/urb.c:478 Now, although submitting an URB while the device is being reset is a questionable thing to do, it shouldn't count as a driver bug as severe as submitting an URB for an endpoint that doesn't exist. Indeed, endpoint 0 always exists, even while the device is in its unconfigured state. To prevent these misleading driver bug reports, this patch updates usb_disable_endpoint() to avoid clearing the ep_in[] and ep_out[] pointers when the endpoint being disabled is ep0. There's no danger of leaving a stale pointer in place, because the usb_host_endpoint structure being pointed to is stored permanently in udev->ep0; it doesn't get deallocated until the entire usb_device structure does. Reported-and-tested-by: syzbot+db339689b2101f6f6071@syzkaller.appspotmail.com Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2005011558590.903-100000@netrider.rowland.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index fcf84bfc08e3..f705ea52eb97 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1143,11 +1143,11 @@ void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr,
if (usb_endpoint_out(epaddr)) {
ep = dev->ep_out[epnum];
- if (reset_hardware)
+ if (reset_hardware && epnum != 0)
dev->ep_out[epnum] = NULL;
} else {
ep = dev->ep_in[epnum];
- if (reset_hardware)
+ if (reset_hardware && epnum != 0)
dev->ep_in[epnum] = NULL;
if (ep) {