From: Florian Westphal <[email protected]>
Date: Fri, 20 Jul 2018 19:30:57 +0200
> Got crash report with following backtrace:
> BUG: unable to handle kernel paging request at ffff8801869daffe
> RIP: 0010:[<ffffffff816429c4>] [<ffffffff816429c4>]
> ip6_finish_output2+0x394/0x4c0
> RSP: 0018:ffff880186c83a98 EFLAGS: 00010283
> RAX: ffff8801869db00e ...
> [<ffffffff81644cdc>] ip6_finish_output+0x8c/0xf0
> [<ffffffff81644d97>] ip6_output+0x57/0x100
> [<ffffffff81643dc9>] ip6_forward+0x4b9/0x840
> [<ffffffff81645566>] ip6_rcv_finish+0x66/0xc0
> [<ffffffff81645db9>] ipv6_rcv+0x319/0x530
> [<ffffffff815892ac>] netif_receive_skb+0x1c/0x70
> [<ffffffffc0060bec>] atl1c_clean+0x1ec/0x310 [atl1c]
> ...
>
> The bad access is in neigh_hh_output(), at skb->data - 16 (HH_DATA_MOD).
> atl1c driver provided skb with no headroom, so 14 bytes (ethernet
> header) got pulled, but then 16 are copied.
>
> Reserve NET_SKB_PAD bytes headroom, like netdev_alloc_skb().
>
> Compile tested only; I lack hardware.
>
> Fixes: 7b7017642199 ("atl1c: Fix misuse of netdev_alloc_skb in refilling rx
> ring")
> Signed-off-by: Florian Westphal <[email protected]>
Ancient bug :-/
Applied and queued up for -stable, thanks Florian.
