From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 AC69E477E58; Thu, 20 Aug 2026 16:26:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243184; cv=none; b=mJoO5mg1wrkl1BTgnMLRjqEwmXd3J5qHzWoKKj44bM97uJjy3CcTQLpU6DRHNRRTR3epXFafY+fj7u/R8MSqmDaPLBMJh8zE1W18WGtZSYOaDVjcrISaEhjlxzaYkR9P/O2NCUA6i57TSH+Kg/OmpmIg2AC6F0TyFLBodpD+E6Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243184; c=relaxed/simple; bh=dD16Aq0+QgaqWqgJuJKMnFGYX02fP7efeXfGWNfMd2Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YEN/ce0E453v+Fz/OwgAvJkcZmzyJwE75Wt0TRVLKBAh2Me7wJIntAdAGDLgY1dQOhldeevMw0ICr/9CWeFWBwUJ+1S6Xb6RjcGITQUhRfhumpzoyiGOi93wZvlshonZBjLeo03TcTV8TV7Ld6oDZeIZlsUOe6ZsH7lrCcE4nKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=y2Vr2rY3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="y2Vr2rY3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C91C21F00A3A; Thu, 20 Aug 2026 16:26:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787243183; bh=DBWkfzktjv6MFHNye3l7zbqJK1uNaavnRAurxhv04f4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=y2Vr2rY3AMDIeyIy/8j5sU/qHKiwQUd0sU1dx58Zwao9GNwNRw1nn3CxvrNCfgsBJ Q5t7ltpoaquLkYGWPcQnVIAE4P5pcNqeM4t4sg9t5s8foDz1Nua/iyz0BZerr7SXZm 71fjNtBsmhbBQpfm9ihpM+/9x7CQXS01Q1Yz1mOI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, AutonomousCodeSecurity@microsoft.com, "Xiang Mei (Microsoft)" , Jozsef Kadlecsik , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.1 279/303] netfilter: ipset: fix refcount race between list:set GC and swap Date: Thu, 20 Aug 2026 16:56:55 +0200 Message-ID: <20260820145301.852797189@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145253.200766705@linuxfoundation.org> References: <20260820145253.200766705@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei (Microsoft) [ Upstream commit 0c88868271653537ed443272dd8e7d13634d214b ] __ip_set_put_byindex() resolved the index to a set pointer under RCU, then took ip_set_ref_lock in __ip_set_put() to decrement set->ref. ip_set_swap() holds that same lock while swapping both the ip_set_list slots and the two sets' ref counters, so it can interleave between the dereference and the lock acquisition, leaving the caller to decrement a set whose reference already moved to the other index and hit BUG_ON(set->ref == 0). list_set_gc() reaches this from timer softirq, which the nfnl mutex does not serialize against swap: an expiring list:set member calls list_set_del() -> ip_set_put_byindex() while IPSET_CMD_SWAP runs on the referenced sets. Resolve the index and decrement under ip_set_ref_lock, as ip_set_swap() already does, keeping the refcount tied to the index rather than to a stale set pointer. kernel BUG at net/netfilter/ipset/ip_set_core.c:685! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ip_set_put_byindex (net/netfilter/ipset/ip_set_core.c:870) Call Trace: list_set_del (net/netfilter/ipset/ip_set_list_set.c:159) set_cleanup_entries (net/netfilter/ipset/ip_set_list_set.c:181) list_set_gc (net/netfilter/ipset/ip_set_list_set.c:578) call_timer_fn (kernel/time/timer.c:1748) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2374) run_timer_softirq (kernel/time/timer.c:2405) Kernel panic - not syncing: Fatal exception in interrupt Fixes: 9076aea76538 ("netfilter: ipset: Increase the number of maximal sets automatically") Reported-by: AutonomousCodeSecurity@microsoft.com Signed-off-by: Xiang Mei (Microsoft) Acked-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/ipset/ip_set_core.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index 7601e4ca02775..70e5ed6d50fe0 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -679,11 +679,18 @@ __ip_set_get(struct ip_set *set) } static void -__ip_set_put(struct ip_set *set) +__ip_set_put_locked(struct ip_set *set) { - write_lock_bh(&ip_set_ref_lock); + lockdep_assert_held(&ip_set_ref_lock); BUG_ON(set->ref == 0); set->ref--; +} + +static void +__ip_set_put(struct ip_set *set) +{ + write_lock_bh(&ip_set_ref_lock); + __ip_set_put_locked(set); write_unlock_bh(&ip_set_ref_lock); } @@ -856,11 +863,11 @@ __ip_set_put_byindex(struct ip_set_net *inst, ip_set_id_t index) { struct ip_set *set; - rcu_read_lock(); - set = rcu_dereference(inst->ip_set_list)[index]; + write_lock_bh(&ip_set_ref_lock); + set = ip_set(inst, index); if (set) - __ip_set_put(set); - rcu_read_unlock(); + __ip_set_put_locked(set); + write_unlock_bh(&ip_set_ref_lock); } void -- 2.53.0