diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-03-04 12:59:18 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-03-05 19:16:56 -0800 |
| commit | f130a0cc1b4ff1ef28a307428d40436032e2b66e (patch) | |
| tree | 2d673795ca94a7a6e3f801e640d1d5238c1db8b5 /net/ipv6/route.c | |
| parent | e0c836820f2f275bc04d28ef417dd9e8711635a9 (diff) | |
inet: fix lwtunnel_valid_encap_type() lock imbalance
After blamed commit rtm_to_fib_config() now calls
lwtunnel_valid_encap_type{_attr}() without RTNL held,
triggering an unlock balance in __rtnl_unlock,
as reported by syzbot [1]
IPv6 and rtm_to_nh_config() are not yet converted.
Add a temporary @rtnl_is_held parameter to lwtunnel_valid_encap_type()
and lwtunnel_valid_encap_type_attr().
While we are at it replace the two rcu_dereference()
in lwtunnel_valid_encap_type() with more appropriate
rcu_access_pointer().
[1]
syz-executor245/5836 is trying to release lock (rtnl_mutex) at:
[<ffffffff89d0e38c>] __rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
but there are no more locks to release!
other info that might help us debug this:
no locks held by syz-executor245/5836.
stack backtrace:
CPU: 0 UID: 0 PID: 5836 Comm: syz-executor245 Not tainted 6.14.0-rc4-syzkaller-00873-g3424291dd242 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_unlock_imbalance_bug+0x25b/0x2d0 kernel/locking/lockdep.c:5289
__lock_release kernel/locking/lockdep.c:5518 [inline]
lock_release+0x47e/0xa30 kernel/locking/lockdep.c:5872
__mutex_unlock_slowpath+0xec/0x800 kernel/locking/mutex.c:891
__rtnl_unlock+0x6c/0xf0 net/core/rtnetlink.c:142
lwtunnel_valid_encap_type+0x38a/0x5f0 net/core/lwtunnel.c:169
lwtunnel_valid_encap_type_attr+0x113/0x270 net/core/lwtunnel.c:209
rtm_to_fib_config+0x949/0x14e0 net/ipv4/fib_frontend.c:808
inet_rtm_newroute+0xf6/0x2a0 net/ipv4/fib_frontend.c:917
rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6919
netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534
netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
sock_sendmsg_nosec net/socket.c:709 [inline]
Fixes: 1dd2af7963e9 ("ipv4: fib: Convert RTM_NEWROUTE and RTM_DELROUTE to per-netns RTNL.")
Reported-by: syzbot+3f18ef0f7df107a3f6a0@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/67c6f87a.050a0220.38b91b.0147.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250304125918.2763514-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv6/route.c')
| -rw-r--r-- | net/ipv6/route.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index ef2d23a1e3d5..fb2e99a56529 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -5128,7 +5128,8 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh, cfg->fc_mp_len = nla_len(tb[RTA_MULTIPATH]); err = lwtunnel_valid_encap_type_attr(cfg->fc_mp, - cfg->fc_mp_len, extack); + cfg->fc_mp_len, + extack, true); if (err < 0) goto errout; } @@ -5147,7 +5148,8 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh, if (tb[RTA_ENCAP_TYPE]) { cfg->fc_encap_type = nla_get_u16(tb[RTA_ENCAP_TYPE]); - err = lwtunnel_valid_encap_type(cfg->fc_encap_type, extack); + err = lwtunnel_valid_encap_type(cfg->fc_encap_type, + extack, true); if (err < 0) goto errout; } |