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| author | Lu Baolu <baolu.lu@linux.intel.com> | 2017-01-03 16:28:46 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-12 10:39:11 (GMT) |
| commit | 9da8e3e48e8805810096f1fbd9e764c0baece561 (patch) | |
| tree | 154df4a98704e68d99a1756b5bd7322b1087522f | |
| parent | 9bdd47c53b7cf79f68ef5038e9494261f060f64e (diff) | |
| download | linux-9da8e3e48e8805810096f1fbd9e764c0baece561.tar.xz | |
usb: xhci: fix possible wild pointer
commit 2b985467371a58ae44d76c7ba12b0951fee6ed98 upstream.
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.
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 797137e..f7431f4 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1271,14 +1271,18 @@ 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) && @@ -1427,6 +1431,8 @@ 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: |