diff options
| author | Florian Westphal <fw@strlen.de> | 2026-08-25 03:36:03 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2026-09-07 18:43:16 +0200 |
| commit | 387d744fa7e499d2c3748a4e60e02ebb24e7fb16 (patch) | |
| tree | c7d8ad19442061dc1635f3bf47bac4ec01309276 | |
| parent | 2c018cc4842c33f0c732962e2ab58635e8ae5823 (diff) | |
netfilter: nfnetlink_log: cope with concurrent instance destruction
Instances are refcounted. However, only memory release happens on the
1 -> 0 transition; the unlink from hashes can occur with any refcount.
Uncooperative userspace can force a situation where a queue is pending
for destruction from netlink event while a different socket with same
portid processes an UNBIND request.
With right timing, this will unhash the instance again:
Oops: general protection fault, [..]
Call Trace:
<TASK>
nfulnl_recv_config+0x31a/0xd50
nfnetlink_rcv_msg+0x7c2/0xeb0
Fixes: 0597f2680d66 ("[NETFILTER]: Add new "nfnetlink_log" userspace packet logging facility")
Reported-by: Eulgyu Kim <eulgyukim@snu.ac.kr>
Reported-by: Jaeyoung Chung <jjy600901@snu.ac.kr>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nfnetlink_log.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 9d7fec570abe..d923f2cb1398 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -228,13 +228,18 @@ static void __nfulnl_flush(struct nfulnl_instance *inst); static void __instance_destroy(struct nfulnl_instance *inst) { + spin_lock(&inst->lock); + if (inst->copy_mode == NFULNL_COPY_DISABLED) { + /* attempt to UNBIND a queue already pending + * destruction via netlink close event. Ignore. + */ + spin_unlock(&inst->lock); + return; + } + /* first pull it out of the global list */ hlist_del_rcu(&inst->hlist); - /* then flush all pending packets from skb */ - - spin_lock(&inst->lock); - /* lockless readers wont be able to use us */ inst->copy_mode = NFULNL_COPY_DISABLED; |