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    SubjectRe: [TIP] BUG kmalloc-4096: Poison overwritten (ath5k_rx_skb_alloc)
    On Wed, Feb 25, 2009 at 02:01:39PM +0000, Sitsofe Wheeler wrote:
    > NAS is the name of a nearby access point. This is really tough to
    > reproduce but if there's anything (e.g. ftrace) I can always turn on
    > that will help you track this thing down let me know. Unfortunately the
    > machine is an EeePC 900 so any logging would have to be cyclic and held
    > in RAM...

    Hmm, I suppose there could be some error paths under memory pressure that
    aren't quite right. Here's one, but I don't think it can cause any problems,
    at least without error spew.

    Looking over the code, perhaps there's a race with ath5k_rx_start,
    namely sc->rxlink is changed out from under the rxbuflock. Still can't
    immediately see a use-after-free there.


    ath5k: don't overwrite bf->skbaddr unless pcu mapping fails.

    diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
    index 1d77ee9..6d91335 100644
    --- a/drivers/net/wireless/ath5k/base.c
    +++ b/drivers/net/wireless/ath5k/base.c
    @@ -1140,12 +1140,14 @@ ath5k_rxbuf_setup(struct ath5k_softc *sc, struct ath5k_buf *bf)
    struct ath5k_hw *ah = sc->ah;
    struct sk_buff *skb = bf->skb;
    struct ath5k_desc *ds;
    + dma_addr_t dma_addr;

    if (!skb) {
    - skb = ath5k_rx_skb_alloc(sc, &bf->skbaddr);
    + skb = ath5k_rx_skb_alloc(sc, &dma_addr);
    if (!skb)
    return -ENOMEM;
    bf->skb = skb;
    + bf->skbaddr = dma_addr;

    Bob Copeland %%

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      Last update: 2009-02-26 02:09    [W:0.033 / U:17.648 seconds]
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