From: Gertjan van Wingerde <gwingerde@xxxxxxxxxxxx> 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: Gertjan van Wingerde <gwingerde@xxxxxxxxxxxx> Signed-off-by: Ivo van Doorn <IvDoorn@xxxxxxxxx> --- drivers/net/wireless/rt2x00/rt2500usb.c | 10 +++------- drivers/net/wireless/rt2x00/rt2x00usb.c | 8 +++----- drivers/net/wireless/rt2x00/rt73usb.c | 10 +++------- 3 files changed, 9 insertions(+), 19 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c index 1bfb68a..9851cef 100644 --- a/drivers/net/wireless/rt2x00/rt2500usb.c +++ b/drivers/net/wireless/rt2x00/rt2500usb.c @@ -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; /* diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c index 6e22036..3080969 100644 --- a/drivers/net/wireless/rt2x00/rt2x00usb.c +++ b/drivers/net/wireless/rt2x00/rt2x00usb.c @@ -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)) @@ -286,16 +287,13 @@ 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 * so we can recycle the existing sk buffer for the new frame. diff --git a/drivers/net/wireless/rt2x00/rt73usb.c b/drivers/net/wireless/rt2x00/rt73usb.c index 800a1e2..505a9f5 100644 --- a/drivers/net/wireless/rt2x00/rt73usb.c +++ b/drivers/net/wireless/rt2x00/rt73usb.c @@ -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; /* -- 1.5.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
