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 A61633C3F4C; Thu, 30 Jul 2026 15:12:27 +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=1785424348; cv=none; b=oZbpxTfCsOuK08k7bokqtEs7U4HXI3AENNj610hX1ngsx9jnST3S4hbl3tjIFlG8PZouhTkZXWzAhmAnhGhOm1LfTHDytXu4r/5P4T0hEkOnXmCQCv5BKzR3MlHVYiWdgrJqrjcAO3+ROhTQhQPYClJwErbHlf42R7Yrgbc3Md0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424348; c=relaxed/simple; bh=9h5sZfzj7yPcQH5PPIeWGrhEKgV4Wcaswf6rEp5mp64=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NCQnDw4hlfDP/zxuKL+2EYrTFCi9JuEISQctHykds/MmHqiNO0qzvdotFbYLjrqMeLvNLxrp7eI3wLZRDnAhB4bPKBj7Ny0aCIes+Ky5VecVr+jZ2yrk6QVJ5LwmFE9tge/uNNLhqTRcGE65cTXKmo9j3V6vbxicYToR1gloWC8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=opsoHjRZ; 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="opsoHjRZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AEAA1F000E9; Thu, 30 Jul 2026 15:12:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785424347; bh=gV0nm4i6mvkTvM7RImfh6AwwOtPQLwfUJIITfFctqLU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=opsoHjRZscR/JqPSrrg06hbYyMsAYqE3UnhkqJVZvbcfDzoqaWsP1g+LM+E72bg5n AGiYE2moyG33YkG0RLv83AfhmnIJ7NTQL5YOsqKKgAmfuERMpVkuDy5vYct/h3wIYI Te7fLGZ4nkg3ebvwrkGMZHU3ss9qkI09vSoT7yyY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chengfeng Ye , Emil Tsalapatis , Jakub Sitnicki , Eduard Zingerman , Sasha Levin Subject: [PATCH 6.18 317/675] bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg() Date: Thu, 30 Jul 2026 16:10:47 +0200 Message-ID: <20260730141451.865327126@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: Chengfeng Ye [ Upstream commit 2d66a033864e27ab8d5e44cb36f31d9d2413bee4 ] tcp_bpf_sendmsg() keeps msg_tx across sk_stream_wait_memory(), which drops and reacquires the socket lock. Its error path tries to decide whether msg_tx names the local temporary message by comparing it with the current value of psock->cork. This comparison is unsafe when two threads send on the same socket: Thread A Thread B msg_tx = psock->cork sk_msg_alloc() fails sk_stream_wait_memory() releases the socket lock acquires the socket lock completes the cork psock->cork = NULL frees the cork reacquires the socket lock msg_tx != psock->cork sk_msg_free(msg_tx) The stale cork is therefore mistaken for the local temporary message and freed again. KASAN reported: BUG: KASAN: slab-use-after-free in sk_msg_free+0x49/0x50 Read of size 4 at addr ffff88810c908800 by task poc/90 Call Trace: sk_msg_free+0x49/0x50 tcp_bpf_sendmsg+0x14f5/0x1cc0 __sys_sendto+0x32c/0x3a0 __x64_sys_sendto+0xdb/0x1b0 Allocated by task 89: __kasan_kmalloc+0x8f/0xa0 tcp_bpf_sendmsg+0x16b3/0x1cc0 Freed by task 91: __kasan_slab_free+0x43/0x70 kfree+0x131/0x3c0 tcp_bpf_sendmsg+0xec3/0x1cc0 msg_tx can only name the stack-local tmp or the shared cork. Check for tmp directly so a changed psock->cork cannot turn a shared message into an apparent local one. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Chengfeng Ye Reviewed-by: Emil Tsalapatis Reviewed-by: Jakub Sitnicki Link: https://lore.kernel.org/bpf/87fr18lmzo.fsf%40cloudflare.com/ Link: https://lore.kernel.org/netdev/20260719161630.2901208-1-nicoyip.dev%40gmail.com/ [v1] Link: https://patch.msgid.link/20260724103856.3399001-1-nicoyip.dev@gmail.com Signed-off-by: Eduard Zingerman Signed-off-by: Sasha Levin --- net/ipv4/tcp_bpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 7a3f0b244c8fc8..c27e797eff275a 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -589,7 +589,7 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) wait_for_memory: err = sk_stream_wait_memory(sk, &timeo); if (err) { - if (msg_tx && msg_tx != psock->cork) + if (msg_tx == &tmp) sk_msg_free(sk, msg_tx); goto out_err; } -- 2.53.0