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>
19cdead3e2