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
......@@ -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.
* Copy descriptor to the skbdesc->desc buffer, making it 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;
memcpy(skbdesc->desc, rxd, skbdesc->desc_len);
rxd = (__le32 *)skbdesc->desc;
/*
......
......@@ -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
......
......@@ -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.
* Copy descriptor to the skbdesc->desc buffer, making it 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;
memcpy(skbdesc->desc, rxd, skbdesc->desc_len);
rxd = (__le32 *)skbdesc->desc;
/*
......
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