Re: [PATCH net] skbuff: Fix skb checksum flag on skb pull
From: Tom Herbert <hidden>
Date: 2015-08-31 23:44:51
On Mon, Aug 31, 2015 at 3:55 PM, Pravin B Shelar [off-list ref] wrote:
quoted hunk ↗ jump to hunk
VXLAN device can receive skb with checksum partial. But the checksum offset could be in outer header which is pulled on receive. Such skb can cause the panic when checksum is calculated on skb. Following patch fixes the bug by setting checksum unnecessary while pulling outer header. ---8<--- [ 13.800141] RIP: 0010:[<ffffffff81518034>] [<ffffffff81518034>] skb_checksum_help+0x144/0x150 [ 13.800141] RSP: 0000:ffff88011fd83940 EFLAGS: 00010292 [ 13.800141] RAX: 0000000000000042 RBX: ffff880114dd56c0 RCX: ffff8801188d9580 ... ... [ 13.852308] Call Trace: [ 13.852308] <IRQ> [ 13.852308] [<ffffffffa0164c28>] queue_userspace_packet+0x408/0x470 [openvswitch] [ 13.852308] [<ffffffffa016614d>] ovs_dp_upcall+0x5d/0x60 [openvswitch] [ 13.852308] [<ffffffffa0166236>] ovs_dp_process_packet_with_key+0xe6/0x100 [openvswitch] [ 13.852308] [<ffffffffa016629b>] ovs_dp_process_received_packet+0x4b/0x80 [openvswitch] [ 13.852308] [<ffffffffa016c51a>] ovs_vport_receive+0x2a/0x30 [openvswitch] [ 13.852308] [<ffffffffa0171383>] vxlan_rcv+0x53/0x60 [openvswitch] [ 13.852308] [<ffffffffa01734cb>] vxlan_udp_encap_recv+0x8b/0xf0 [openvswitch] [ 13.852308] [<ffffffff8157addc>] udp_queue_rcv_skb+0x2dc/0x3b0 [ 13.852308] [<ffffffff8157b56f>] __udp4_lib_rcv+0x1cf/0x6c0 [ 13.852308] [<ffffffff8157ba7a>] udp_rcv+0x1a/0x20 [ 13.852308] [<ffffffff8154fdbd>] ip_local_deliver_finish+0xdd/0x280 [ 13.852308] [<ffffffff81550128>] ip_local_deliver+0x88/0x90 [ 13.852308] [<ffffffff8154fa7d>] ip_rcv_finish+0x10d/0x370 [ 13.852308] [<ffffffff81550365>] ip_rcv+0x235/0x300 [ 13.852308] [<ffffffff8151ba1d>] __netif_receive_skb+0x55d/0x620 [ 13.852308] [<ffffffff8151c360>] netif_receive_skb+0x80/0x90 [ 13.852308] [<ffffffff81459935>] virtnet_poll+0x555/0x6f0 [ 13.852308] [<ffffffff8151cd04>] net_rx_action+0x134/0x290 [ 13.852308] [<ffffffff810683d8>] __do_softirq+0xa8/0x210 [ 13.852308] [<ffffffff8162fe6c>] call_softirq+0x1c/0x30 [ 13.852308] [<ffffffff810161a5>] do_softirq+0x65/0xa0 [ 13.852308] [<ffffffff810687be>] irq_exit+0x8e/0xb0 [ 13.852308] [<ffffffff81630733>] do_IRQ+0x63/0xe0 [ 13.852308] [<ffffffff81625f2e>] common_interrupt+0x6e/0x6e [ 13.852308] <EOI> [ 13.852308] [<ffffffff8162dc02>] ? system_call_fastpath+0x16/0x1b Reported-by: Anupam Chanda <redacted> Signed-off-by: Pravin B Shelar <redacted> --- include/linux/skbuff.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 9b88536..6238e9f 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h@@ -2601,6 +2601,9 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb, { if (skb->ip_summed == CHECKSUM_COMPLETE) skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0)); + else if (skb->ip_summed == CHECKSUM_PARTIAL && + skb_checksum_start_offset(skb) <= len) + skb->ip_summed = CHECKSUM_UNNECESSARY;
No, this isn't right. We should never be converting CHECKSUM_PARTIAL into CHECKSUM_UNNECESSARY.
} unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html