diff options
| author | Tuan Do <tuan@calif.io> | 2026-04-03 00:33:17 -0700 |
|---|---|---|
| committer | Florian Westphal <fw@strlen.de> | 2026-04-08 13:34:16 +0200 |
| commit | f8dca15a1b190787bbd03285304b569631160eda (patch) | |
| tree | c4292e7c2f63c63f7dec5b8e5e79f859b1744ffb /net/netfilter | |
| parent | fdce0b3590f724540795b874b4c8850c90e6b0a8 (diff) | |
netfilter: nft_ct: fix use-after-free in timeout object destroy
nft_ct_timeout_obj_destroy() frees the timeout object with kfree()
immediately after nf_ct_untimeout(), without waiting for an RCU grace
period. Concurrent packet processing on other CPUs may still hold
RCU-protected references to the timeout object obtained via
rcu_dereference() in nf_ct_timeout_data().
Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer
freeing until after an RCU grace period, matching the approach already
used in nfnetlink_cttimeout.c.
KASAN report:
BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0
Read of size 4 at addr ffff8881035fe19c by task exploit/80
Call Trace:
nf_conntrack_tcp_packet+0x1381/0x29d0
nf_conntrack_in+0x612/0x8b0
nf_hook_slow+0x70/0x100
__ip_local_out+0x1b2/0x210
tcp_sendmsg_locked+0x722/0x1580
__sys_sendto+0x2d8/0x320
Allocated by task 75:
nft_ct_timeout_obj_init+0xf6/0x290
nft_obj_init+0x107/0x1b0
nf_tables_newobj+0x680/0x9c0
nfnetlink_rcv_batch+0xc29/0xe00
Freed by task 26:
nft_obj_destroy+0x3f/0xa0
nf_tables_trans_destroy_work+0x51c/0x5c0
process_one_work+0x2c4/0x5a0
Fixes: 7e0b2b57f01d ("netfilter: nft_ct: add ct timeout support")
Cc: stable@vger.kernel.org
Signed-off-by: Tuan Do <tuan@calif.io>
Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'net/netfilter')
| -rw-r--r-- | net/netfilter/nft_ct.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index 128ff8155b5d..04c74ccf9b84 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -1020,7 +1020,7 @@ static void nft_ct_timeout_obj_destroy(const struct nft_ctx *ctx, nf_queue_nf_hook_drop(ctx->net); nf_ct_untimeout(ctx->net, timeout); nf_ct_netns_put(ctx->net, ctx->family); - kfree(priv->timeout); + kfree_rcu(priv->timeout, rcu); } static int nft_ct_timeout_obj_dump(struct sk_buff *skb, |