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 4CC89A59; Wed, 30 Sep 2026 18:09:35 +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=1790791776; cv=none; b=FS3BTNtU4Yy2ltAPOzxgvAQWsm71K3NYWQf0HdlWMhiEK5NDJ/87gpyllHofkdBCphY0FgfZiESU5aNezo/S0hG6UcyZn8swwfolR9MUrEUq1TegzEULeoem2leq+lsjeUcv2iqfFQWzG6woKLim2DHCAVzRNHsgSBVcHgap2GM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791776; c=relaxed/simple; bh=gp4YgiENxc3lc+hFYJtHkBBh7uQ2Xwd17eqF8LtG6Tc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FE5/nJ4m5hWd33XXIAoABW2tYFjF2Bhj8A7qC/I0oYH/SjRAzm8MNwd9W+8x6eFTCeuT64DVflVt7A/JYaL5rSwh8xa7jp4W5q/gMWTM86o/hkF5UCnsxhafNFeHt13Rlt6SyVLx7gcUCpk+lPi0crBBxnM39hG/u+44HTK22CU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aOkumKy6; 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="aOkumKy6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EEF91F000FF; Wed, 30 Sep 2026 18:09:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791774; bh=U6tWXBr28C9Hstv4K2Uk8Xkx5rUkv9F/HE2sLHSre7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aOkumKy6wNt86uLbcNs8COo7Ruwc5kwjNLxKruG3MPLoMm/vNxx6bq65ucvDoeylU OSQ8FEqVESiH8M4VF0nTEnseJpG2Y6Glsyy0eMg7hPy2jL9tmmHuqY4O7cLsoz7kFS C/OmtTr21eeGOPdaloUbWKibltaAKCnnyLhc9B+Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Xuanqiang Luo , Paolo Abeni , Dmitriy Okunev Subject: [PATCH 5.15 414/752] fou: Fix use-after-free in fou_create() Date: Wed, 30 Sep 2026 17:24:44 +0200 Message-ID: <20260930152407.235480864@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xuanqiang Luo commit b14361aca6350ff7907b0e9903c7b94dc7d5d4a0 upstream. fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release(). Fixes: 23461551c006 ("fou: Support for foo-over-udp RX path") Suggested-by: Kuniyuki Iwashima Link: https://lore.kernel.org/netdev/20260502031401.3557229-12-kuniyu@google.com/ Cc: stable@vger.kernel.org Signed-off-by: Xuanqiang Luo Link: https://patch.msgid.link/20260722083858.182506-1-xuanqiang.luo@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Dmitriy Okunev Signed-off-by: Greg Kroah-Hartman --- net/ipv4/fou_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/fou_core.c +++ b/net/ipv4/fou_core.c @@ -639,9 +639,9 @@ static int fou_create(struct net *net, s return 0; error: - kfree(fou); if (sock) udp_tunnel_sock_release(sock); + kfree_rcu(fou, rcu); return err; }