linux-kernel - [PATCH 1/2] usb: host: xhci: Fix possible wild pointer when handling abort command

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Date:   Mon,  5 Dec 2016 15:51:49 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     mathias.nyman@...el.com, gregkh@...uxfoundation.org
Cc:     baolu.lu@...ux.intel.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, broonie@...nel.org,
        baolin.wang@...aro.org
Subject: [PATCH 1/2] usb: host: xhci: Fix possible wild pointer when handling abort command

When current command was supposed to be aborted, host will free the command
in handle_cmd_completion() function. But it might be still referenced by
xhci->current_cmd, which need to set NULL.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
This patch is based on Lu Baolu's new fix patch:
usb: xhci: fix possible wild pointer
https://www.spinics.net/lists/linux-usb/msg150219.html
---
 drivers/usb/host/xhci-ring.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 62dd1c7..9965a4c 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1362,8 +1362,11 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 	 */
 	if (cmd_comp_code == COMP_CMD_ABORT) {
 		xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
-		if (cmd->status == COMP_CMD_ABORT)
+		if (cmd->status == COMP_CMD_ABORT) {
+			if (xhci->current_cmd == cmd)
+				xhci->current_cmd = NULL;
 			goto event_handled;
+		}
 	}
 
 	cmd_type = TRB_FIELD_TO_TYPE(le32_to_cpu(cmd_trb->generic.field[3]));
-- 
1.7.9.5