On 2017年10月26日 22:11, Eric Dumazet wrote:
On Thu, Oct 26, 2017 at 5:15 AM, Jason Wang <jasow...@redhat.com> wrote:An unaligned alloc_frag->offset caused by previous allocation will result an unaligned skb->head. This will lead unaligned skb_shared_info and then unaligned dataref which requires to be aligned for accessing on some architecture. Fix this by aligning alloc_frag->offset before the frag refilling. Fixes: 0bbd7dad34f8 ("tun: make tun_build_skb() thread safe") Cc: Eric Dumazet <eduma...@google.com> Cc: Willem de Bruijn <willemdebruijn.ker...@gmail.com> Cc: Wei Wei <dotwe...@gmail.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Mark Rutland <mark.rutl...@arm.com> Reported-by: Wei Wei <dotwe...@gmail.com> Signed-off-by: Jason Wang <jasow...@redhat.com> --- - The patch is needed for -stable. - Wei, can you try this patch to see if it solves your issue? --- drivers/net/tun.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index b9973fb..60e44f2 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1286,6 +1286,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, buflen += SKB_DATA_ALIGN(len + pad); rcu_read_unlock(); + alloc_frag->offset = ALIGN((u64)alloc_frag->offset, TUN_RX_PAD);You have to align to one cache line (SMP_CACHE_BYTES), or SKB_DATA_ALIGN(1)
Oh right.
Then eventually use skb_reserve() for NET_IP_ALIGN, but I guess it is already done.
Yes. Thanks
