4.4-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 19cdead3e2ef8ed765c5d1ce48057ca9d97b5094 ]
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 54ef31371407 ("[PATCH] bonding: Handle large hard_header_len") but the panic can be triggered only since commit fc791b633515 ("IB/ipoib: move back IB LL address into the hard header").
Reported-by: Norbert P noe@physik.uzh.ch Fixes: 54ef31371407 ("[PATCH] bonding: Handle large hard_header_len") Fixes: fc791b633515 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/bonding/bond_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -1107,11 +1107,11 @@ static void bond_compute_features(struct gso_max_size = min(gso_max_size, slave->dev->gso_max_size); gso_max_segs = min(gso_max_segs, slave->dev->gso_max_segs); } + bond_dev->hard_header_len = max_hard_header_len;
done: bond_dev->vlan_features = vlan_features; bond_dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL; - bond_dev->hard_header_len = max_hard_header_len; bond_dev->gso_max_segs = gso_max_segs; netif_set_gso_max_size(bond_dev, gso_max_size);