From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Alan Stern <stern@rowland.harvard.edu>,
Aman Deep <aman.deep@samsung.com>,
Jeffy Chen <jeffy.chen@rock-chips.com>
Subject: [PATCH 4.4 13/22] usb: ohci: Proper handling of ed_rm_list to handle race condition between usb_kill_urb() and finish_unlinks()
Date: Mon, 26 Feb 2018 21:16:13 +0100 [thread overview]
Message-ID: <20180226201559.317507165@linuxfoundation.org> (raw)
In-Reply-To: <20180226201558.681421374@linuxfoundation.org>
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: AMAN DEEP <aman.deep@samsung.com>
commit 46408ea558df13b110e0866b99624384a33bdeba upstream.
There is a race condition between finish_unlinks->finish_urb() function
and usb_kill_urb() in ohci controller case. The finish_urb calls
spin_unlock(&ohci->lock) before usb_hcd_giveback_urb() function call,
then if during this time, usb_kill_urb is called for another endpoint,
then new ed will be added to ed_rm_list at beginning for unlink, and
ed_rm_list will point to newly added.
When finish_urb() is completed in finish_unlinks() and ed->td_list
becomes empty as in below code (in finish_unlinks() function):
if (list_empty(&ed->td_list)) {
*last = ed->ed_next;
ed->ed_next = NULL;
} else if (ohci->rh_state == OHCI_RH_RUNNING) {
*last = ed->ed_next;
ed->ed_next = NULL;
ed_schedule(ohci, ed);
}
The *last = ed->ed_next will make ed_rm_list to point to ed->ed_next
and previously added ed by usb_kill_urb will be left unreferenced by
ed_rm_list. This causes usb_kill_urb() hang forever waiting for
finish_unlink to remove added ed from ed_rm_list.
The main reason for hang in this race condtion is addition and removal
of ed from ed_rm_list in the beginning during usb_kill_urb and later
last* is modified in finish_unlinks().
As suggested by Alan Stern, the solution for proper handling of
ohci->ed_rm_list is to remove ed from the ed_rm_list before finishing
any URBs. Then at the end, we can add ed back to the list if necessary.
This properly handle the updated ohci->ed_rm_list in usb_kill_urb().
Fixes: 977dcfdc6031 ("USB: OHCI: don't lose track of EDs when a controller dies")
Acked-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: Aman Deep <aman.deep@samsung.com>
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/host/ohci-q.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
--- a/drivers/usb/host/ohci-q.c
+++ b/drivers/usb/host/ohci-q.c
@@ -1018,6 +1018,8 @@ skip_ed:
* have modified this list. normally it's just prepending
* entries (which we'd ignore), but paranoia won't hurt.
*/
+ *last = ed->ed_next;
+ ed->ed_next = NULL;
modified = 0;
/* unlink urbs as requested, but rescan the list after
@@ -1076,21 +1078,22 @@ rescan_this:
goto rescan_this;
/*
- * If no TDs are queued, take ED off the ed_rm_list.
+ * If no TDs are queued, ED is now idle.
* Otherwise, if the HC is running, reschedule.
- * If not, leave it on the list for further dequeues.
+ * If the HC isn't running, add ED back to the
+ * start of the list for later processing.
*/
if (list_empty(&ed->td_list)) {
- *last = ed->ed_next;
- ed->ed_next = NULL;
ed->state = ED_IDLE;
list_del(&ed->in_use_list);
} else if (ohci->rh_state == OHCI_RH_RUNNING) {
- *last = ed->ed_next;
- ed->ed_next = NULL;
ed_schedule(ohci, ed);
} else {
- last = &ed->ed_next;
+ ed->ed_next = ohci->ed_rm_list;
+ ohci->ed_rm_list = ed;
+ /* Don't loop on the same ED */
+ if (last == &ohci->ed_rm_list)
+ last = &ed->ed_next;
}
if (modified)
next prev parent reply other threads:[~2018-02-26 20:16 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 20:16 [PATCH 4.4 00/22] 4.4.119-stable review Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 01/22] netfilter: drop outermost socket lock in getsockopt() Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 02/22] powerpc/64s: Fix RFI flush dependency on HARDLOCKUP_DETECTOR Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 03/22] PCI: keystone: Fix interrupt-controller-node lookup Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 04/22] ip_tunnel: replace dst_cache with generic implementation Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 05/22] ip_tunnel: fix preempt warning in ip tunnel creation/updating Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 06/22] xtensa: fix high memory/reserved memory collision Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 07/22] scsi: ibmvfc: fix misdefined reserved field in ibmvfc_fcp_rsp_info Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 08/22] cfg80211: fix cfg80211_beacon_dup Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 09/22] iio: buffer: check if a buffer has been set up when poll is called Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 10/22] iio: adis_lib: Initialize trigger before requesting interrupt Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 11/22] x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 12/22] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise_softirq() Greg Kroah-Hartman
2018-02-26 20:16 ` Greg Kroah-Hartman [this message]
2018-02-26 20:16 ` [PATCH 4.4 14/22] arm64: Disable unhandled signal log messages by default Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 15/22] Add delay-init quirk for Corsair K70 RGB keyboards Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 16/22] drm/edid: Add 6 bpc quirk for CPT panel in Asus UX303LA Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 17/22] usb: dwc3: gadget: Set maxpacket size for ep0 IN Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 18/22] usb: ldusb: add PIDs for new CASSY devices supported by this driver Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 19/22] usb: gadget: f_fs: Process all descriptors during bind Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 20/22] usb: renesas_usbhs: missed the "running" flag in usb_dmac with rx path Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 21/22] drm/amdgpu: Avoid leaking PM domain on driver unbind (v2) Greg Kroah-Hartman
2018-02-26 20:16 ` [PATCH 4.4 22/22] binder: add missing binder_unlock() Greg Kroah-Hartman
2018-02-27 0:08 ` [PATCH 4.4 00/22] 4.4.119-stable review Nathan Chancellor
2018-02-27 13:10 ` Greg Kroah-Hartman
2018-02-27 0:56 ` Shuah Khan
2018-02-27 4:18 ` kernelci.org bot
2018-02-27 7:17 ` Naresh Kamboju
2018-02-27 10:56 ` Guenter Roeck
2018-02-27 18:33 ` Greg Kroah-Hartman
2018-02-27 14:55 ` Guenter Roeck
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