IB/ipoib: Clear IPCB before icmp_send

IPCB should be cleared before icmp_send, since it may contain data from
previous layers and the data could be misinterpreted as ip header options,
which later caused the ihl to be set to an invalid value and resulted in
the following stack corruption:

[ 1083.031512] ib0: packet len 57824 (> 2048) too long to send, dropping
[ 1083.031843] ib0: packet len 37904 (> 2048) too long to send, dropping
[ 1083.032004] ib0: packet len 4040 (> 2048) too long to send, dropping
[ 1083.032253] ib0: packet len 63800 (> 2048) too long to send, dropping
[ 1083.032481] ib0: packet len 23960 (> 2048) too long to send, dropping
[ 1083.033149] ib0: packet len 63800 (> 2048) too long to send, dropping
[ 1083.033439] ib0: packet len 63800 (> 2048) too long to send, dropping
[ 1083.033700] ib0: packet len 63800 (> 2048) too long to send, dropping
[ 1083.034124] ib0: packet len 63800 (> 2048) too long to send, dropping
[ 1083.034387] ==================================================================
[ 1083.034602] BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0xf08/0x1310
[ 1083.034798] Write of size 4 at addr ffff880353457c5f by task kworker/u16:0/7
[ 1083.034990]
[ 1083.035104] CPU: 7 PID: 7 Comm: kworker/u16:0 Tainted: G           O      4.19.0-rc5+ #1
[ 1083.035316] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu2 04/01/2014
[ 1083.035573] Workqueue: ipoib_wq ipoib_cm_skb_reap [ib_ipoib]
[ 1083.035750] Call Trace:
[ 1083.035888]  dump_stack+0x9a/0xeb
[ 1083.036031]  print_address_description+0xe3/0x2e0
[ 1083.036213]  kasan_report+0x18a/0x2e0
[ 1083.036356]  ? __ip_options_echo+0xf08/0x1310
[ 1083.036522]  __ip_options_echo+0xf08/0x1310
[ 1083.036688]  icmp_send+0x7b9/0x1cd0
[ 1083.036843]  ? icmp_route_lookup.constprop.9+0x1070/0x1070
[ 1083.037018]  ? netif_schedule_queue+0x5/0x200
[ 1083.037180]  ? debug_show_all_locks+0x310/0x310
[ 1083.037341]  ? rcu_dynticks_curr_cpu_in_eqs+0x85/0x120
[ 1083.037519]  ? debug_locks_off+0x11/0x80
[ 1083.037673]  ? debug_check_no_obj_freed+0x207/0x4c6
[ 1083.037841]  ? check_flags.part.27+0x450/0x450
[ 1083.037995]  ? debug_check_no_obj_freed+0xc3/0x4c6
[ 1083.038169]  ? debug_locks_off+0x11/0x80
[ 1083.038318]  ? skb_dequeue+0x10e/0x1a0
[ 1083.038476]  ? ipoib_cm_skb_reap+0x2b5/0x650 [ib_ipoib]
[ 1083.038642]  ? netif_schedule_queue+0xa8/0x200
[ 1083.038820]  ? ipoib_cm_skb_reap+0x544/0x650 [ib_ipoib]
[ 1083.038996]  ipoib_cm_skb_reap+0x544/0x650 [ib_ipoib]
[ 1083.039174]  process_one_work+0x912/0x1830
[ 1083.039336]  ? wq_pool_ids_show+0x310/0x310
[ 1083.039491]  ? lock_acquire+0x145/0x3a0
[ 1083.042312]  worker_thread+0x87/0xbb0
[ 1083.045099]  ? process_one_work+0x1830/0x1830
[ 1083.047865]  kthread+0x322/0x3e0
[ 1083.050624]  ? kthread_create_worker_on_cpu+0xc0/0xc0
[ 1083.053354]  ret_from_fork+0x3a/0x50

For instance __ip_options_echo is failing to proceed with invalid srr and
optlen passed from another layer via IPCB

[  762.139568] IPv4: __ip_options_echo rr=0 ts=0 srr=43 cipso=0
[  762.139720] IPv4: ip_options_build: IPCB 00000000f3cd969e opt 000000002ccb3533
[  762.139838] IPv4: __ip_options_echo in srr: optlen 197 soffset 84
[  762.139852] IPv4: ip_options_build srr=0 is_frag=0 rr_needaddr=0 ts_needaddr=0 ts_needtime=0 rr=0 ts=0
[  762.140269] ==================================================================
[  762.140713] IPv4: __ip_options_echo rr=0 ts=0 srr=0 cipso=0
[  762.141078] BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0x12ec/0x1680
[  762.141087] Write of size 4 at addr ffff880353457c7f by task kworker/u16:0/7
Signed-off-by: Denis Drozdov <denisd@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/ipoib/ipoib_cm.c

@@ -1438,11 +1438,15 @@ static void ipoib_cm_skb_reap(struct work_struct *work)
 		spin_unlock_irqrestore(&priv->lock, flags);
 		netif_tx_unlock_bh(dev);
 
-		if (skb->protocol == htons(ETH_P_IP))
+		if (skb->protocol == htons(ETH_P_IP)) {
+			memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 			icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
+		}
 #if IS_ENABLED(CONFIG_IPV6)
-		else if (skb->protocol == htons(ETH_P_IPV6))
+		else if (skb->protocol == htons(ETH_P_IPV6)) {
+			memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+		}
 #endif
 		dev_kfree_skb_any(skb);