On 12/21/10 03:41, Ismael Luceno wrote:
> Backtrace:
> rt2800usb_write_tx_data
> rt2x00queue_write_tx_frame
> rt2x00mac_tx
> invoke_tx_handlers
> __ieee80211_tx
> ieee80211_tx
> virt_to_head_page
> ieee80211_xmit
> ieee80211_tx_skb
> ieee80211_scan_work
> schedule
> ieee80211_scan_work
> process_one_work
> ...
>
> It tried to expand the skb past it's end using skb_put. So I replaced it
> with a call to skb_padto, which takes the issue into account.
>
> Signed-off-by: Ismael Luceno <ismael.luceno@xxxxxxxxx>
> ---
> drivers/net/wireless/rt2x00/rt2800usb.c | 16 ++++++++++++----
> 1 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/wireless/rt2x00/rt2800usb.c b/drivers/net/wireless/rt2x00/rt2800usb.c
> index 3e0205d..b97a4a5 100644
> --- a/drivers/net/wireless/rt2x00/rt2800usb.c
> +++ b/drivers/net/wireless/rt2x00/rt2800usb.c
> @@ -369,7 +369,10 @@ static void rt2800usb_write_tx_desc(struct queue_entry *entry,
> static void rt2800usb_write_tx_data(struct queue_entry *entry,
> struct txentry_desc *txdesc)
> {
> - u8 padding_len;
> + unsigned int len;
> + int err;
> +
> + rt2800_write_tx_data(entry, txdesc);
>
> /*
> * pad(1~3 bytes) is added after each 802.11 payload.
> @@ -378,9 +381,14 @@ static void rt2800usb_write_tx_data(struct queue_entry *entry,
> * | TXINFO | TXWI | 802.11 header | L2 pad | payload | pad | USB end pad |
> * |<------------- tx_pkt_len ------------->|
> */
> - rt2800_write_tx_data(entry, txdesc);
> - padding_len = roundup(entry->skb->len + 4, 4) - entry->skb->len;
> - memset(skb_put(entry->skb, padding_len), 0, padding_len);
> + len = roundup(entry->skb->len, 4) + 4;
> + err = skb_padto(entry->skb, len);
> + if (unlikely(err)) {
> + WARNING(entry->queue->rt2x00dev, "TX SKB padding error, out of memory\n");
> + return;
> + }
> +
> + entry->skb->len = len;
> }
>
> /*
Why did you change the computation of the length?
To me, looking at the original code, the correct computation should be:
len = roundup(entry->skb->len + 4, 4);
Now it seems we sometimes include padding where we don't have to (and thus
potentially have to expand the buffer when we won't have to).
---
Gertjan.
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