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 B189D473C6D; Fri, 7 Aug 2026 15:41:47 +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=1786117308; cv=none; b=F0cr9qELRjKAZsgJwkFdFUqp6gVBR3Ah2viuyPPNZ/rQHhOLiQBAdqlkF9O9s5yspsQUBqn7To43KZYoyQ6iyTjp1dkGRhBkuGExfKDWoxNLu1NkMx+utHkFWAWjv12705HsLHsydRmF3krKmbh3u9Nz379XHjqwdey84dXVA9U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786117308; c=relaxed/simple; bh=r0q4NVJeXp2A/VbC6axAbLB6i/QdZN7Rfn3SYLF/FhQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G9tT+kPgY+iRAnrRr/oqRZ8052PVeXHVwRo6wWBpzhQ4MUUdpLeh/wE+tAhkC8swGt7npkl8ug7jW+qU3vxrN8JQWGFh/n6VhfeTP3OETHVeNL/Y4uISRXqhi5y9cZsMtKCJNhOMsXhfauEn+MnqG/r+pyAbMdEUrJYasmHLY/Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fXKrc1+X; 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="fXKrc1+X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD7231F000E9; Fri, 7 Aug 2026 15:41:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786117307; bh=0L40yF2kBgJRSCjxt/QV4eUTro+CQx1ogjEnkX9U1y0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fXKrc1+X8mX1jUbx2yfhZT33XPWqsT16G2RuF1LnVX6ILaL3GCPjVUlMd3J/Isjwe mZZG1GvvoFE1OxnHFKclMo7Rr4HQZr2AYGmahTafAUt2ddZDX6dlDSuYYaZfKQtuaC ZTN/eZU77O9pDOa21rWajP3enkW4m6DXAyOtoCKU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Xuanqiang Luo , Paolo Abeni Subject: [PATCH 7.1 274/438] fou: Fix use-after-free in fou_create() Date: Fri, 7 Aug 2026 16:37:50 +0200 Message-ID: <20260807143433.823967225@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143428.008222056@linuxfoundation.org> References: <20260807143428.008222056@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 7.1-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: 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 @@ -629,9 +629,9 @@ static int fou_create(struct net *net, s return 0; error: - kfree(fou); if (sock) udp_tunnel_sock_release(sock->sk); + kfree_rcu(fou, rcu); return err; }