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Commit a26cbc65 authored by Gertjan van Wingerde's avatar Gertjan van Wingerde Committed by John W. Linville
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rt2x00: Fix double usage of skb->cb in USB RX path. 



It is not safe to use the skb->cb area for both the rxd and
skb_frame_desc data at the same time, while they occupy an overlapping
piece of memory. This can lead to hard to trace crashes as pointers
within skb_frame_desc are pointing into nowhere, or the rxd data is
overwritten with non-sense.

Fix it by copying the rxd to a small buffer on the stack.

Signed-off-by: default avatarGertjan van Wingerde <gwingerde@kpnplanet.nl>
Signed-off-by: default avatarIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 239c249d

drivers/net/wireless/rt2x00/rt2500usb.c

+3 −7
Original line number Diff line number Diff line
@@ -1156,14 +1156,10 @@ static void rt2500usb_fill_rxdone(struct queue_entry *entry, 
	u32 word1;



	/*

	 * Copy descriptor to the skb->cb array, this has 2 benefits:

	 * 1) Each descriptor word is 4 byte aligned.

	 * 2) Descriptor is safe  from moving of frame data in rt2x00usb.

	 */

	skbdesc->desc_len =

	    min_t(u16, entry->queue->desc_size, sizeof(entry->skb->cb));

	memcpy(entry->skb->cb, rxd, skbdesc->desc_len);

	skbdesc->desc = entry->skb->cb;

	 * Copy descriptor to the skbdesc->desc buffer, making it safe from moving of

	 * frame data in rt2x00usb.

	 */

	memcpy(skbdesc->desc, rxd, skbdesc->desc_len);

	rxd = (__le32 *)skbdesc->desc;



	/*

drivers/net/wireless/rt2x00/rt2x00usb.c

+3 −5
Original line number Diff line number Diff line
@@ -267,6 +267,7 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) 
	struct sk_buff *skb;

	struct skb_frame_desc *skbdesc;

	struct rxdone_entry_desc rxdesc;

	u8 rxd[32];



	if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags) ||

	    !test_and_clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags))
@@ -286,15 +287,12 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) 
	skbdesc = get_skb_frame_desc(entry->skb);

	memset(skbdesc, 0, sizeof(*skbdesc));

	skbdesc->entry = entry;

	skbdesc->desc = rxd;

	skbdesc->desc_len = entry->queue->desc_size;



	memset(&rxdesc, 0, sizeof(rxdesc));

	rt2x00dev->ops->lib->fill_rxdone(entry, &rxdesc);



	/*

	 * Trim the skb to the correct size.

	 */

	skb_trim(entry->skb, rxdesc.size);



	/*

	 * Allocate a new sk buffer to replace the current one.

	 * If allocation fails, we should drop the current frame

drivers/net/wireless/rt2x00/rt73usb.c

+3 −7
Original line number Diff line number Diff line
@@ -1428,14 +1428,10 @@ static void rt73usb_fill_rxdone(struct queue_entry *entry, 
	u32 word1;



	/*

	 * Copy descriptor to the skb->cb array, this has 2 benefits:

	 * 1) Each descriptor word is 4 byte aligned.

	 * 2) Descriptor is safe  from moving of frame data in rt2x00usb.

	 */

	skbdesc->desc_len =

	    min_t(u16, entry->queue->desc_size, sizeof(entry->skb->cb));

	memcpy(entry->skb->cb, rxd, skbdesc->desc_len);

	skbdesc->desc = entry->skb->cb;

	 * Copy descriptor to the skbdesc->desc buffer, making it safe from moving of

	 * frame data in rt2x00usb.

	 */

	memcpy(skbdesc->desc, rxd, skbdesc->desc_len);

	rxd = (__le32 *)skbdesc->desc;



	/*