Vivek Kumar Bhagat <[email protected]> writes: > Dear Bjorn, > >>> This is wrong. There are usbnet minidrivers depending on info->tx_fixup >>> being called with a NULL skb. > I am using ax88179_178a driver and not familiar with usbnet minidrivers. > When ax88179_tx_fixup() is called with NULL skb from > usbnet_start_xmit(), I get a kernel crash. > Backtrace: > 09:14:569>[0-553.5598] [<befaa194>] (ax88179_tx_fixup+0x0/0x16c > [ax88179_178a]) from [<befef7a8>] (usbnet_start_xmit+0xa > 09:14:569>0/0x420 [usbnet]) > 09:14:570>[0-553.5711] r6:cb5ec280 r5:00000000 r4:cb5ebd40 > 09:14:572>[0-553.5755] [<befef708>] (usbnet_start_xmit+0x0/0x420 > [usbnet]) from [<c0400040>] (dev_hard_start_xmit+0x2ec/ > 09:14:572>0x558) > 09:14:572>[0-553.5858] [<c03ffd54>] (dev_hard_start_xmit+0x0/0x558) > In case skb NULL check can not be added in usbnet_start_xmit() > then NULL check is required in ax88179_tx_fixup() or asix_tx_fixup().
Yes. Or you could add the check to usbnet_start_xmit() if you remove the ugly hack in the minidrivers calling usbnet_start_xmit with skb == NULL first. This is cdc_ncm and those depending on cdc_ncm. But it would also be interesting to know why ax88179_tx_fixup() is called with a NULL skb. I believe this should not happen. Do you have any idea? cdc_ncm, which is the driver depending on the NULL skb input, will explicitly call usbnet_start_xmit(NULL, dev->net); I don't know any other way this could happen. Bjørn -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
