From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6DFC3A2579; Wed, 8 Apr 2026 16:35:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775666139; cv=none; b=FVdMHAxXfTeaxKKO4fpMOHu2Mq+5KetGRfbIFvvJK1Hk/KwPRiXOWYZJNJM+Hy3cSymxkzFC3YWwxuwg/pMu0x3UvPV3wNZl0LtcsOT7LP/5+iyHVgauX0NCjJi9uDvLQzDcaJGLMZG0oTCWRTMXBkaGbD4HoX0UEW2AWKDLr6Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775666139; c=relaxed/simple; bh=5c50JljN0nyluFTWQSs1lEg6gg+uEZ2+0xi27FPAPNE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CJ1Fc/Vp9KiXP60GECNTJQVL/8LDwfrrJMKPQHSzo71jxMQBqeSNYhAfRigEduu2lo4q0owmSy2kour63OjnF91BTVIseUpwGzTRxiaEoUWaC3DWmgeUdLCQrYKwRrRsNcUBLR6vQGDNTaGnNGxictIsUoDVtYbIOysC/cDx0Kw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc Received: by Chamillionaire.breakpoint.cc (Postfix, from userid 1003) id 0786A60560; Wed, 08 Apr 2026 18:35:37 +0200 (CEST) From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , pablo@netfilter.org Subject: [PATCH net 5/7] netfilter: nft_ct: fix use-after-free in timeout object destroy Date: Wed, 8 Apr 2026 18:35:10 +0200 Message-ID: <20260408163512.30537-6-fw@strlen.de> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260408163512.30537-1-fw@strlen.de> References: <20260408163512.30537-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tuan Do 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 Signed-off-by: Florian Westphal --- include/net/netfilter/nf_conntrack_timeout.h | 1 + net/netfilter/nft_ct.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/net/netfilter/nf_conntrack_timeout.h b/include/net/netfilter/nf_conntrack_timeout.h index 9fdaba911de6..3a66d4abb6d6 100644 --- a/include/net/netfilter/nf_conntrack_timeout.h +++ b/include/net/netfilter/nf_conntrack_timeout.h @@ -14,6 +14,7 @@ struct nf_ct_timeout { __u16 l3num; const struct nf_conntrack_l4proto *l4proto; + struct rcu_head rcu; char data[]; }; 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, -- 2.52.0