| Message ID | 20241121194105.3632507-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] rtnetlink: fix rtnl_dump_ifinfo() error path | expand |
On Thu, Nov 21, 2024 at 07:41:05PM +0000, Eric Dumazet wrote: > 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: 43c7ce69d28e ("rtnetlink: Protect struct rtnl_link_ops with SRCU.") > Reported-by: syzbot <syzkaller@googlegroups.com> > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Joe Damato <jdamato@fastly.com>
From: Eric Dumazet <edumazet@google.com> Date: Thu, 21 Nov 2024 19:41:05 +0000 > 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: 43c7ce69d28e ("rtnetlink: Protect struct rtnl_link_ops with SRCU.") > Reported-by: syzbot <syzkaller@googlegroups.com> > Signed-off-by: Eric Dumazet <edumazet@google.com> I missed the error paths, thanks! Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index dd142f444659d9a5da084bddb26736b1602cc2cb..58df76fe408a4677db52a3c1f94674119dc4c925 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -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 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) 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);
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: 43c7ce69d28e ("rtnetlink: Protect struct rtnl_link_ops with SRCU.") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> --- net/core/rtnetlink.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)