From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E355433E7F for ; Sat, 4 Jul 2026 17:14:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783185272; cv=none; b=d294LrXeKVWIK4GvmzhXNlPmIxIxGk1lER33EK2D7CIzUasqb3Q+4K0uncURKOYyaPQjBU+lMTNCikxljyRrYRgeFiJMFFkon3Xyi9LHB2e/TkEj4aDKBhqZakzn3wzd/9MM3pOG0hrmgEkMOWULnHTf3GnTXAKPDU4Emjo+S+0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783185272; c=relaxed/simple; bh=7uyRPvzkXYfs2wmtaHMDG+n85HN/ZOLukoEk4n9DqyE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ecPxE0I5ZF2HYYD9IFYMnJF8vv7CPcI2RAmsM1ZGIo4+0q3i4f0jzsfn/597q8kHldkzLHZG93LePSjID1qQphHoH38ospPT3uATG5dJcQUCAcqPkM8WipKLyH3yWurWgiQ7qPf77FmRjyz72NOlIHK0RZ0GOXUs34dQtegiu2o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Jqkj9LAV; arc=none smtp.client-ip=209.85.214.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Jqkj9LAV" Received: by mail-pl1-f182.google.com with SMTP id d9443c01a7336-2c9b42be8feso16005565ad.2 for ; Sat, 04 Jul 2026 10:14:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1783185270; x=1783790070; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=lmrMGneNXYFXj/2nN+KzQAgQlOxhvv+qqZjYjmSo2X4=; b=Jqkj9LAVOrNovQ3dXVETqcNxFMeImz3XGUpDl5pAPkfsUB/rVa0FeJUl2c8pOpeV/Q 20TsBv8Gbj2HBXsAgcrp+2gGSyEVEHpA8NymzzVsr1SQ4Hr3i1H2Bv0DZK5rozNXgsLn 8bo+4yQF+IuRiCLet4j05GWMWbnYH/kZO8VjWy1yx9LImWnzgIrwJVusgSYiJh2EE6Wr yVU93uX5qmDJg1xLydFzfaVoidPKt1v8XcZ9xmUb65Fuqyth1WvQvBw+aMc3grzqo2XC /FbcnWidxP8dxp/f+cA8jOLM/HWsh3TAGR154wAkzBh666YAHMpXZJLLd345+YewJ9H6 GWAg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783185270; x=1783790070; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=lmrMGneNXYFXj/2nN+KzQAgQlOxhvv+qqZjYjmSo2X4=; b=Bprm404ru0+aQKocgKrkJN7P194jfWUk+cy+I75JQVsISVhAGpGGEMgLSe3cQnP/44 4lkvAELIjoO8vRX/K+WzfA66y3gQJSQ2hH8Bd5gYdQLFT7xg9FMn6fXHNV+BRA8DUnBS NWCQdl42wLuAeVuGAIdMQXhnboxM9t3idgXesu9pTq7wvO2IKXdjDAB8ZSvUNRY9fiK8 3PM8x5XZ2JnWNIAct6zDP0Uf+V4/K5JXaGztD7BazRW5nhRrbXN4aos/PdwDnaFxC04S OFwfV8ytzOIUEDtkLU3wF0LuhNpZnMyMkUVLdzvTeIPe0j+VTZduoIUzXeiX/eYKCzSV hGVg== X-Gm-Message-State: AOJu0Yzk2t1nMFYe5z3gOi0Fr6BkGV9DPRQUQ8kY5BbfotcEN2OTitnz lUQpE0TNiN9f4AEH9ndpFIBn0HxKD/1yH47v38nKZ4o2aa1rpAjjRPeUaQIASj3USUc= X-Gm-Gg: AfdE7cljMm97/48+5CNLLExD8I8d6LVEHUH10MiFUgG7SdRwMDonCxrDjwXKlTYVbHr 9tuKyabBQRxUca9Q9TvtteRt4+rigVJzBREp8b0TYGGPz/dKswc/C5/XLptHULIe6sIzQSE/EOU LcxcVcyUjpKExqsEXMiVqU79NIEX/NPuQUNVbRtBwYty724pDbuOzQtm151NobcUoPzmA54LVIN PoVICuAbKyXhqOnyxqnd7pXyBVO5fCTJxWvzH9k6wg4FmMy59C48LjHQTUjC8bLXLPzKl3F0evi 3DUYOlxpD0lQw/c1zRun3pfHkxPLcJ8zOfp9rn8q8alramhkojC+L9YTL6UlP/8vnwLyYXp8MoM Fbqtz61guSn8RM7pqajF1WOnV1HTMSRefL9qrIopQF0NeOJ5UmxxmymzMjyqtaTMLkyrH2T8DW3 4BTrb0THJG4nWdRXa7HSbiJiKTQfMdJzxYdQ/tEpsMISkS1rJF0geIlFPJDQ== X-Received: by 2002:a17:903:b8f:b0:2c9:cf41:adf9 with SMTP id d9443c01a7336-2cbb9f0eb2amr39212645ad.47.1783185270387; Sat, 04 Jul 2026 10:14:30 -0700 (PDT) Received: from fx.tailc0aff1.ts.net ([206.206.192.132]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13b446a766asm35140615c88.7.2026.07.04.10.14.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Jul 2026 10:14:29 -0700 (PDT) From: Weiming Shi To: netdev@vger.kernel.org Cc: dsahern@kernel.org, idosch@nvidia.com, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net, horms@kernel.org, xmei5@asu.edu, linux-kernel@vger.kernel.org, Weiming Shi Subject: [PATCH net] ipv4: fib: free fib_alias with kfree_rcu() on insert error path Date: Sat, 4 Jul 2026 10:14:21 -0700 Message-ID: <20260704171421.1786806-1-bestswngs@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit fib_table_insert() publishes new_fa into the leaf's fa_list with fib_insert_alias() before calling the fib entry notifiers. When a notifier fails, the error path removes new_fa with fib_remove_alias() (hlist_del_rcu) and frees it right away with kmem_cache_free(). fib_table_lookup() walks that list under rcu_read_lock() only, so a concurrent lookup that already reached new_fa keeps reading it after the free: BUG: KASAN: slab-use-after-free in fib_table_lookup (net/ipv4/fib_trie.c:1601) Read of size 1 at addr ffff88810676d4eb by task exploit/297 Call Trace: fib_table_lookup (net/ipv4/fib_trie.c:1601) ip_route_output_key_hash_rcu (net/ipv4/route.c:2814) ip_route_output_key_hash (net/ipv4/route.c:2705) __ip4_datagram_connect (net/ipv4/datagram.c:49) udp_connect (net/ipv4/udp.c:2144) __sys_connect (net/socket.c:2167) __x64_sys_connect (net/socket.c:2173) do_syscall_64 entry_SYSCALL_64_after_hwframe which belongs to the cache ip_fib_alias of size 56 Triggering the error path needs CAP_NET_ADMIN and a registered fib notifier that can reject a route; a netdevsim device whose IPv4 FIB resource is exhausted is enough. Free new_fa with alias_free_mem_rcu(), as fib_table_delete() already does for a fib_alias removed from the trie. Fixes: a6c76c17df02 ("ipv4: Notify route after insertion to the routing table") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi --- net/ipv4/fib_trie.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 1308213791f1..2dc87e2156d3 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1385,7 +1385,7 @@ int fib_table_insert(struct net *net, struct fib_table *tb, out_remove_new_fa: fib_remove_alias(t, tp, l, new_fa); out_free_new_fa: - kmem_cache_free(fn_alias_kmem, new_fa); + alias_free_mem_rcu(new_fa); out: fib_release_info(fi); err: -- 2.43.0