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 497883D6CB4; Wed, 30 Sep 2026 19:17:19 +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=1790795840; cv=none; b=m07ywWddJToRYD9b5Hreu+BNdp2+hybruF0n7cFZBmRJUA+Zmwee92qqUoZ3rO78/BL3DR3xctzXKm0cIbnVN/NLWmsh5B46G+FIdKzsNOITt5UO8sBL0hPuYqLCYLtmJ9vTOmAEBwwSnj4hLNPDO1DQIoulQXrdaJuDsJqjPFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795840; c=relaxed/simple; bh=sqGbHgu27nSCz62vNCHObZRVqIMq6RHAp37Om3olsnw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Tl6bdPVhlKAmeLWecE8vgWZBeUCG0BBIxxZ3g0v79cGtfLnUxUxcIaA82mnwYnefY4Ukg/fmh3JILl0GGvVm0P0VVplyEApxC7p/yihKfxg/w0a0cW5L+3b6l/x+DzPksNmrKEeIgV/k0xJgkjMb267tUVWJTv46O72NsDPTvj0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0J4QlY9V; 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="0J4QlY9V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F79B1F000FF; Wed, 30 Sep 2026 19:17:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795839; bh=GAjJVXC/a7SKLY2LANZhkkjGo8VetoWc4gUFNM9YUww=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0J4QlY9VcgTjyXNnr7tCCfj+7CLd5vzNef+xeeK3Tv5baom0K85X7c7REAiYVP6lS qlJGMuWxgxZYq2eaqYcj1DfMOQU+MvQLr6MJPogJ+SIIiVgQEbNOaTtv1H4W4Jf0a4 D5/dksxMskY1cIARiOdsgAK9tDylk1JD/N217dAs= 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 6.6 0700/1193] fou: Fix use-after-free in fou_create() Date: Wed, 30 Sep 2026 17:23:04 +0200 Message-ID: <20260930152449.803153782@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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 6.6-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 @@ -636,9 +636,9 @@ 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; }