tuntap: properly align skb->head before building skb
authorJason Wang <jasowang@redhat.com>
Fri, 27 Oct 2017 03:05:44 +0000 (11:05 +0800)
committerDavid S. Miller <davem@davemloft.net>
Sat, 28 Oct 2017 10:05:28 +0000 (19:05 +0900)
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 <edumazet@google.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Wei Wei <dotweiba@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reported-by: Wei Wei <dotweiba@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

index b9973fb868b79d5df8cea35780a4575703e70a53..5550f56cb895f7cb5a2c3ff5e93be79bd012e627 100644 (file)
@@ -1286,6 +1286,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
        buflen += SKB_DATA_ALIGN(len + pad);
+       alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
        if (unlikely(!skb_page_frag_refill(buflen, alloc_frag, GFP_KERNEL)))
                return ERR_PTR(-ENOMEM);