4.4-stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal fw@strlen.de
[ Upstream commit 6e56830776828d8ca9897fc4429eeab47c3bb432 ]
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 fw@strlen.de Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c @@ -1683,6 +1683,7 @@ static struct sk_buff *atl1c_alloc_skb(s skb = build_skb(page_address(page) + adapter->rx_page_offset, adapter->rx_frag_size); if (likely(skb)) { + skb_reserve(skb, NET_SKB_PAD); adapter->rx_page_offset += adapter->rx_frag_size; if (adapter->rx_page_offset >= PAGE_SIZE) adapter->rx_page = NULL;