From: Ido Schimmel idosch@mellanox.com
[ Upstream commit b5141915b5aec3b29a63db869229e3741ebce258 ]
The commit cited below removed the RCU read-side critical section from rtnl_fdb_dump() which means that the ndo_fdb_dump() callback is invoked without RCU protection.
This results in the following warning [1] in the VXLAN driver, which relied on the callback being invoked from an RCU read-side critical section.
Fix this by calling rcu_read_lock() in the VXLAN driver, as already done in the bridge driver.
[1] WARNING: suspicious RCU usage 5.8.0-rc4-custom-01521-g481007553ce6 #29 Not tainted ----------------------------- drivers/net/vxlan.c:1379 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1 1 lock held by bridge/166: #0: ffffffff85a27850 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0xea/0x1090
stack backtrace: CPU: 1 PID: 166 Comm: bridge Not tainted 5.8.0-rc4-custom-01521-g481007553ce6 #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack+0x100/0x184 lockdep_rcu_suspicious+0x153/0x15d vxlan_fdb_dump+0x51e/0x6d0 rtnl_fdb_dump+0x4dc/0xad0 netlink_dump+0x540/0x1090 __netlink_dump_start+0x695/0x950 rtnetlink_rcv_msg+0x802/0xbd0 netlink_rcv_skb+0x17a/0x480 rtnetlink_rcv+0x22/0x30 netlink_unicast+0x5ae/0x890 netlink_sendmsg+0x98a/0xf40 __sys_sendto+0x279/0x3b0 __x64_sys_sendto+0xe6/0x1a0 do_syscall_64+0x54/0xa0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fe14fa2ade0 Code: Bad RIP value. RSP: 002b:00007fff75bb5b88 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00005614b1ba0020 RCX: 00007fe14fa2ade0 RDX: 000000000000011c RSI: 00007fff75bb5b90 RDI: 0000000000000003 RBP: 00007fff75bb5b90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00005614b1b89160 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Fixes: 5e6d24358799 ("bridge: netlink dump interface at par with brctl") Signed-off-by: Ido Schimmel idosch@mellanox.com Reviewed-by: Jiri Pirko jiri@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/vxlan.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 09f0b53b2b77..69d9bb88cfd2 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -975,6 +975,7 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb, for (h = 0; h < FDB_HASH_SIZE; ++h) { struct vxlan_fdb *f;
+ rcu_read_lock(); hlist_for_each_entry_rcu(f, &vxlan->fdb_head[h], hlist) { struct vxlan_rdst *rd;
@@ -987,12 +988,15 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb, cb->nlh->nlmsg_seq, RTM_NEWNEIGH, NLM_F_MULTI, rd); - if (err < 0) + if (err < 0) { + rcu_read_unlock(); goto out; + } skip: *idx += 1; } } + rcu_read_unlock(); } out: return err;