linux-stable/drivers/net/bonding
Paolo Abeni 19cdead3e2 bonding: avoid defaulting hard_header_len to ETH_HLEN on slave removal
On slave list updates, the bonding driver computes its hard_header_len
as the maximum of all enslaved devices's hard_header_len.
If the slave list is empty, e.g. on last enslaved device removal,
ETH_HLEN is used.

Since the bonding header_ops are set only when the first enslaved
device is attached, the above can lead to header_ops->create()
being called with the wrong skb headroom in place.

If bond0 is configured on top of ipoib devices, with the
following commands:

ifup bond0
for slave in $BOND_SLAVES_LIST; do
	ip link set dev $slave nomaster
done
ping -c 1 <ip on bond0 subnet>

we will obtain a skb_under_panic() with a similar call trace:
	skb_push+0x3d/0x40
	push_pseudo_header+0x17/0x30 [ib_ipoib]
	ipoib_hard_header+0x4e/0x80 [ib_ipoib]
	arp_create+0x12f/0x220
	arp_send_dst.part.19+0x28/0x50
	arp_solicit+0x115/0x290
	neigh_probe+0x4d/0x70
	__neigh_event_send+0xa7/0x230
	neigh_resolve_output+0x12e/0x1c0
	ip_finish_output2+0x14b/0x390
	ip_finish_output+0x136/0x1e0
	ip_output+0x76/0xe0
	ip_local_out+0x35/0x40
	ip_send_skb+0x19/0x40
	ip_push_pending_frames+0x33/0x40
	raw_sendmsg+0x7d3/0xb50
	inet_sendmsg+0x31/0xb0
	sock_sendmsg+0x38/0x50
	SYSC_sendto+0x102/0x190
	SyS_sendto+0xe/0x10
	do_syscall_64+0x67/0x180
	entry_SYSCALL64_slow_path+0x25/0x25

This change addresses the issue avoiding updating the bonding device
hard_header_len when the slaves list become empty, forbidding to
shrink it below the value used by header_ops->create().

The bug is there since commit 54ef313714 ("[PATCH] bonding: Handle large
hard_header_len") but the panic can be triggered only since
commit fc791b6335 ("IB/ipoib: move back IB LL address into the hard
header").

Reported-by: Norbert P <noe@physik.uzh.ch>
Fixes: 54ef313714 ("[PATCH] bonding: Handle large hard_header_len")
Fixes: fc791b6335 ("IB/ipoib: move back IB LL address into the hard header")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-28 16:04:05 -04:00
..
bond_3ad.c bonding: prevent out of bound accesses 2016-07-01 06:06:09 -04:00
bond_alb.c net: bonding: Flip to the new dev walk API 2016-10-18 11:44:58 -04:00
bond_debugfs.c net: Move bonding headers under include/net 2014-11-10 13:27:49 -05:00
bond_main.c bonding: avoid defaulting hard_header_len to ETH_HLEN on slave removal 2017-04-28 16:04:05 -04:00
bond_netlink.c bonding: set carrier off for devices created through netlink 2016-07-14 16:17:43 -07:00
bond_options.c sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
bond_procfs.c bonding: Display LACP info only to CAP_NET_ADMIN capable user 2015-06-23 03:11:52 -07:00
bond_sysfs.c sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
bond_sysfs_slave.c bonding: export slave's partner_oper_port_state via sysfs and netlink 2015-06-15 16:40:24 -07:00
bonding_priv.h net/bonding: Make DRV macros private 2015-04-26 22:59:53 -04:00
Makefile