On Wed, May 12, 2010 at 8:59 AM, Ivo Van Doorn <ivdoorn@xxxxxxxxx> wrote:
> On Tue, May 11, 2010 at 11:51 PM, Gertjan van Wingerde
> <gwingerde@xxxxxxxxx> wrote:
>> The buffer address descriptor word is not part of the TXINFO structure
>> needed for beacons. The current writing of that word for beacons is
>> therefore an out-of-bounds write.
>> Fix this by only writing the buffer address descriptor word for TX
>> queues.
>>
>> Signed-off-by: Gertjan van Wingerde <gwingerde@xxxxxxxxx>
>> ---
>> drivers/net/wireless/rt2x00/rt61pci.c | 10 +++++-----
>> 1 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/wireless/rt2x00/rt61pci.c b/drivers/net/wireless/rt2x00/rt61pci.c
>> index 2436363..99c2981 100644
>> --- a/drivers/net/wireless/rt2x00/rt61pci.c
>> +++ b/drivers/net/wireless/rt2x00/rt61pci.c
>> @@ -1801,12 +1801,12 @@ static void rt61pci_write_tx_desc(struct rt2x00_dev *rt2x00dev,
>> rt2x00_set_field32(&word, TXD_W5_WAITING_DMA_DONE_INT, 1);
>> rt2x00_desc_write(txd, 5, word);
>>
>> - rt2x00_desc_read(txd, 6, &word);
>> - rt2x00_set_field32(&word, TXD_W6_BUFFER_PHYSICAL_ADDRESS,
>> - skbdesc->skb_dma);
>> - rt2x00_desc_write(txd, 6, word);
>> + if (txdesc->queue != QID_BEACON) {
>> + rt2x00_desc_read(txd, 6, &word);
>> + rt2x00_set_field32(&word, TXD_W6_BUFFER_PHYSICAL_ADDRESS,
>> + skbdesc->skb_dma);
>> + rt2x00_desc_write(txd, 6, word);
>>
>> - if (skbdesc->desc_len > TXINFO_SIZE) {
>> rt2x00_desc_read(txd, 11, &word);
>> rt2x00_set_field32(&word, TXD_W11_BUFFER_LENGTH0,
>> txdesc->length);
>
> Shouldn't the check for TXINFO_SIZE be used rather than explicitly
> checking for the QID?
>
I agree that this is a change that didn't have to be made in this patch.
However, after patch 4 of the series we cannot depend on the
skbdesc->desc_len being set anymore, and we would have to depend on
checking the QID anyway.
Note that in reality these two checks are completely equivalent with
respect to the result.
---
Gertjan.
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