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From:   Mayank Rana <quic_mrana@quicinc.com>
To:     <peter.chen@kernel.org>, <balbi@kernel.org>,
        <gregkh@linuxfoundation.org>
CC:     <linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>,
        Mayank Rana <quic_mrana@quicinc.com>
Subject: [PATCH] xhci: Use xhci_get_virt_ep() to validate ep_index
Date:   Thu, 28 Apr 2022 11:47:52 -0700
Message-ID: <1651171672-9774-1-git-send-email-quic_mrana@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

ring_doorbell_for_active_rings() API is being called from
multiple context. This specific API tries to get virt_dev
based endpoint using passed slot_id and ep_index. Some caller
API is having check against slot_id and ep_index using
xhci_get_virt_ep() API whereas xhci_handle_cmd_config_ep() API
only check ep_index against -1 value but not upper bound i.e.
EP_CTX_PER_DEV. Hence use xhci_get_virt_ep() API to get virt_dev
based endpoint which checks both slot_id and ep_index to get
valid endpoint.

Signed-off-by: Mayank Rana <quic_mrana@quicinc.com>
---
 drivers/usb/host/xhci-ring.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index d0b6806..3bab4f3 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -62,6 +62,9 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
 			 u32 field1, u32 field2,
 			 u32 field3, u32 field4, bool command_must_succeed);
 
+static struct xhci_virt_ep *xhci_get_virt_ep(struct xhci_hcd *xhci,
+			unsigned int slot_id, unsigned int ep_index);
+
 /*
  * Returns zero if the TRB isn't in this segment, otherwise it returns the DMA
  * address of the TRB.
@@ -457,7 +460,9 @@ static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
 	unsigned int stream_id;
 	struct xhci_virt_ep *ep;
 
-	ep = &xhci->devs[slot_id]->eps[ep_index];
+	ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
+	if (!ep)
+		return;
 
 	/* A ring has pending URBs if its TD list is not empty */
 	if (!(ep->ep_state & EP_HAS_STREAMS)) {
-- 
2.7.4