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 EC29D29BD87; Thu, 30 Jul 2026 15:00:57 +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=1785423659; cv=none; b=PUIdwvPWt3ty5rsUxnnY0MhFRB51q34kH6CuuTZJAVFs9NbjWHrSExrIsS+7V1ANlrZoBsg09QlO6mSB+rOPSOruV6I0AyeRB9PqFLXn1gOfDXUESthtEJDG7IzUsa5IOIFTqyLVM70lT5aDmUBk5D9A2LWq0VLV8r6s+VgHOzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423659; c=relaxed/simple; bh=ZWty/qbBNd4GxFCLOSTGXfjM9xwg5kRtUsB/y2vhcXE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VWSa7rXewLocfG1gOkL8Diqe9A5UFr8vfHXVcKqdHhFh9l9qz/xoHH/5Dn9SykVj1eeFMI9OycN/mBmSq1jn9oYgkhKWrFtU3L8n/PlfV3QSd7iqLvJ4esW7WX91bwHtPFJj9fM2/Fl/gJi9OTPqnVobh145qaUbI8nGcfakwy4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T1jcGclt; 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="T1jcGclt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 112001F000E9; Thu, 30 Jul 2026 15:00:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423657; bh=Nj5UDoFs5KTjoYDhhLfGlqZDvVmxKCUrJhtm+hwEOQU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=T1jcGcltVheE5OND84lLUgWv2GTBiM13W4pdpbs+8yHA3VhEQXFdVJP4jeoD9cjs4 zgJ1IKlBdNx43KL/0dP4xaOppjGIl1lCG+O8RIMjyWU1NaqNCItE1fo6YyHUHBnOMb B1T4eIoEfDKmsvtvk8YopM38n+KHkmZgNaopP3Rw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Michal Luczaj , Jakub Sitnicki , John Fastabend , Kumar Kartikeya Dwivedi , Sasha Levin Subject: [PATCH 6.18 119/675] bpf, sockmap: Reject unhashed UDP sockets on sockmap update Date: Thu, 30 Jul 2026 16:07:29 +0200 Message-ID: <20260730141447.673309166@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michal Luczaj [ Upstream commit 66efd3368ae10d05e08fbe6425b50fdec7186ac7 ] UDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means sk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false. Because sockmap accepts unbound UDP sockets, a BPF program can increment a socket's refcount via lookup. If the socket is subsequently bound, the transition from unbound to bound causes bpf_sk_release() to skip the decrement of the refcount, causing a memory leak. unreferenced object 0xffff88810bc2eb40 (size 1984): comm "test_progs", pid 2451, jiffies 4295320596 hex dump (first 32 bytes): 7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00 ................ 02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace (crc bdee079d): kmem_cache_alloc_noprof+0x557/0x660 sk_prot_alloc+0x69/0x240 sk_alloc+0x30/0x460 inet_create+0x2ce/0xf80 __sock_create+0x25b/0x5c0 __sys_socket+0x119/0x1d0 __x64_sys_socket+0x72/0xd0 do_syscall_64+0xa1/0x5f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Instead of special-casing for refcounted sockets, reject unhashed UDP sockets during sockmap updates, as there is no benefit to supporting those. This effectively reverts the commit under Fixes, with two exceptions: 1. sock_map_sk_state_allowed() maintains a fall-through `return true`. 2. In the spirit of commit b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage"), the proto::unhash BPF handler is not reintroduced. Historical note: this issue is related to commit 67312adc96b5 ("bpf: reject unhashed sockets in bpf_sk_assign"). Fixes: 0c48eefae712 ("sock_map: Lift socket state restriction for datagram sockets") Suggested-by: Kuniyuki Iwashima Signed-off-by: Michal Luczaj Reviewed-by: Kuniyuki Iwashima Reviewed-by: Jakub Sitnicki Reviewed-by: John Fastabend Link: https://lore.kernel.org/bpf/20260707-sockmap-lookup-udp-leak-v4-2-f878346f27ab@rbox.co Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Sasha Levin --- net/core/sock_map.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 5947b38e4f8b6f..70bbc78fb079f7 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -542,6 +542,8 @@ static bool sock_map_sk_state_allowed(const struct sock *sk) { if (sk_is_tcp(sk)) return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_LISTEN); + if (sk_is_udp(sk)) + return sk_hashed(sk); if (sk_is_stream_unix(sk)) return (1 << sk->sk_state) & TCPF_ESTABLISHED; if (sk_is_vsock(sk) && -- 2.53.0