diff options
| author | Ido Schimmel <idosch@nvidia.com> | 2025-12-21 17:48:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-01-08 12:14:35 +0300 |
| commit | ee4183501ea556dca31f5ffd8690aa9fd25b609f (patch) | |
| tree | b52a2ada28088f58b07778ede7be0b150acb4524 /net/ipv4 | |
| parent | bf3709738d8a8cc6fa275773170c5c29511a0b24 (diff) | |
| download | linux-ee4183501ea556dca31f5ffd8690aa9fd25b609f.tar.xz | |
ipv4: Fix reference count leak when using error routes with nexthop objects
[ Upstream commit ac782f4e3bfcde145b8a7f8af31d9422d94d172a ]
When a nexthop object is deleted, it is marked as dead and then
fib_table_flush() is called to flush all the routes that are using the
dead nexthop.
The current logic in fib_table_flush() is to only flush error routes
(e.g., blackhole) when it is called as part of network namespace
dismantle (i.e., with flush_all=true). Therefore, error routes are not
flushed when their nexthop object is deleted:
# ip link add name dummy1 up type dummy
# ip nexthop add id 1 dev dummy1
# ip route add 198.51.100.1/32 nhid 1
# ip route add blackhole 198.51.100.2/32 nhid 1
# ip nexthop del id 1
# ip route show
blackhole 198.51.100.2 nhid 1 dev dummy1
As such, they keep holding a reference on the nexthop object which in
turn holds a reference on the nexthop device, resulting in a reference
count leak:
# ip link del dev dummy1
[ 70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2
Fix by flushing error routes when their nexthop is marked as dead.
IPv6 does not suffer from this problem.
Fixes: 493ced1ac47c ("ipv4: Allow routes to use nexthop objects")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Closes: https://lore.kernel.org/netdev/d943f806-4da6-4970-ac28-b9373b0e63ac@I-love.SAKURA.ne.jp/
Reported-by: syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20251221144829.197694-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/fib_trie.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index cc86031d2050..658f26d9a9ec 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2059,10 +2059,11 @@ int fib_table_flush(struct net *net, struct fib_table *tb, bool flush_all) continue; } - /* Do not flush error routes if network namespace is - * not being dismantled + /* When not flushing the entire table, skip error + * routes that are not marked for deletion. */ - if (!flush_all && fib_props[fa->fa_type].error) { + if (!flush_all && fib_props[fa->fa_type].error && + !(fi->fib_flags & RTNH_F_DEAD)) { slen = fa->fa_slen; continue; } |