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rtnetlink: fix rtnl_dump_ifinfo() error path

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syzbot found that rtnl_dump_ifinfo() could return with a lock held [1]

Move code around so that rtnl_link_ops_put() and put_net()
can be called at the end of this function.

[1]
WARNING: lock held when returning to user space!
6.12.0-rc7-syzkaller-01681-g38f83a57aa8e #0 Not tainted
syz-executor399/5841 is leaving the kernel with locks still held!
1 lock held by syz-executor399/5841:
  #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
  #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
  #0: ffffffff8f46c2a0 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x22/0x250 net/core/rtnetlink.c:555

Fixes: 43c7ce69d2 ("rtnetlink: Protect struct rtnl_link_ops with SRCU.")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20241121194105.3632507-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-11-21 19:41:05 +00:00 committed by Jakub Kicinski
parent 078f644cb8
commit 9b234a97b1
1 changed files with 10 additions and 4 deletions
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14
net/core/rtnetlink.c
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@ -2442,7 +2442,9 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
tgt_net = rtnl_get_net_ns_capable(skb->sk, netnsid);
if (IS_ERR(tgt_net)) {
NL_SET_ERR_MSG(extack, "Invalid target network namespace id");
return PTR_ERR(tgt_net);
err = PTR_ERR(tgt_net);
netnsid = -1;
goto out;
}
break;
case IFLA_EXT_MASK:
@ -2457,7 +2459,8 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
default:
if (cb->strict_check) {
NL_SET_ERR_MSG(extack, "Unsupported attribute in link dump request");
return -EINVAL;
err = -EINVAL;
goto out;
}
}
}
@ -2479,11 +2482,14 @@ walk_entries:
break;
}
if (kind_ops)
rtnl_link_ops_put(kind_ops, ops_srcu_index);
cb->seq = tgt_net->dev_base_seq;
nl_dump_check_consistent(cb, nlmsg_hdr(skb));
out:
if (kind_ops)
rtnl_link_ops_put(kind_ops, ops_srcu_index);
if (netnsid >= 0)
put_net(tgt_net);