diff options
| author | Lu Baolu <baolu.lu@linux.intel.com> | 2017-01-03 18:28:46 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-03 17:37:32 +0100 |
| commit | 2b985467371a58ae44d76c7ba12b0951fee6ed98 (patch) | |
| tree | df6c8bbae1e165624af259bb8de5c1d77a4aeb60 | |
| parent | 28bedb5ae463b9f7e5195cbc93f1795e374bdef8 (diff) | |
| download | linux-2b985467371a58ae44d76c7ba12b0951fee6ed98.tar.gz linux-2b985467371a58ae44d76c7ba12b0951fee6ed98.tar.bz2 linux-2b985467371a58ae44d76c7ba12b0951fee6ed98.zip | |
usb: xhci: fix possible wild pointer
handle_cmd_completion() frees a command structure which might be still
referenced by xhci->current_cmd.
This might cause problem when xhci->current_cmd is accessed after that.
A real-life case could be like this. The host takes a very long time to
respond to a command, and the command timer is fired at the same time
when the command completion event arrives. The command completion
handler frees xhci->current_cmd before the timer function can grab
xhci->lock. Afterward, timer function grabs the lock and go ahead with
checking and setting members of xhci->current_cmd.
Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index bdf6b13d9b67..acc37311c938 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1267,14 +1267,18 @@ void xhci_handle_command_timeout(unsigned long data) bool second_timeout = false; xhci = (struct xhci_hcd *) data; - /* mark this command to be cancelled */ spin_lock_irqsave(&xhci->lock, flags); - if (xhci->current_cmd) { - if (xhci->current_cmd->status == COMP_CMD_ABORT) - second_timeout = true; - xhci->current_cmd->status = COMP_CMD_ABORT; + + if (!xhci->current_cmd) { + spin_unlock_irqrestore(&xhci->lock, flags); + return; } + /* mark this command to be cancelled */ + if (xhci->current_cmd->status == COMP_CMD_ABORT) + second_timeout = true; + xhci->current_cmd->status = COMP_CMD_ABORT; + /* Make sure command ring is running before aborting it */ hw_ring_state = xhci_read_64(xhci, &xhci->op_regs->cmd_ring); if ((xhci->cmd_ring_state & CMD_RING_STATE_RUNNING) && @@ -1422,6 +1426,8 @@ static void handle_cmd_completion(struct xhci_hcd *xhci, xhci->current_cmd = list_entry(cmd->cmd_list.next, struct xhci_command, cmd_list); mod_timer(&xhci->cmd_timer, jiffies + XHCI_CMD_DEFAULT_TIMEOUT); + } else if (xhci->current_cmd == cmd) { + xhci->current_cmd = NULL; } event_handled: |