From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793701135; b=mQkMHNeCWrLRoWuOGX+QwoL5dUczcDdYzIQCzqZp/tPEhS5NWqn+73lTrFIOAlvRSqn1 ZTART2mOzayVenmR7Nhm6MKnoFiE8MOkzWzDs6ZkDenPMZBAyXuqg2RNu9OJrBrW5J9y3 libZYtGU9s9gEBjTV5MlE5s3BbIqntS9AXZ5y1JaSZJCKYzA+MXGwRkL8xEA1NhoK210T cG/0Zqxtx6LTqwAghUBzdYcK1SPW8AgvNoDcTxVu8nfLZU9BZNCt844T3Pb9fQSczHrb/ OxkTiyFak6xbhtTT2i4MSjoJJZD8z2f0+j0cq2BpPvziE9rPzXy78d4SVMMCGWUiPKg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793701135; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=AmhtfT2cw6klcxweVyh5MSW3meA3NirDk4xPYJ6ck2A=; b=F3OKI5koYBoTncMB55THctzRugSw8WfrCU+j0FVsVdpXEg+s0IKZSg6mbiK0dzIeLYbz 8K1tn3QfyXwEPgtVrMFKH6uJ3HvYjwQyz9CTF+JufUTjnSh+pTE0ThAnJjbibxjuLc5ab itfoLrR9Ummmpk1KjQz47YI/tjFsoQjkgs3w6oWIy7tKHYAjM+NXK9P6pX1HOaqmStnLJ b4hsKWkSxfnxaIK7nLpcre83ZOZm4oKKlo10ge9J6c0KtmNscxPr9bYM2slUKNFBgPTpC zanVRncDgY8baNeTEyUkXsLTxm8LNpBATrqt7dpOwLkaetRmG+GSg3TVeSlC2l1qNgQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=EHauTMez; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9EEBE608508E for ; Tue, 3 Nov 2026 10:18:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=EHauTMez Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25EBA1F000C1; Tue, 3 Nov 2026 10:18:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793701135; bh=AmhtfT2cw6klcxweVyh5MSW3meA3NirDk4xPYJ6ck2A=; h=Subject:To:Cc:From:Date; b=EHauTMezlrVYnI3D8DXmcnPw4k+tKLf/7ijx/nthfPaDvyRCQigCIg+G+kXOoMtVv mtCKCJpUZ3H55XNNi9HiSKrwXSse9sr2Q7Cr5PsAgHWPOUt8viYRht4po5M7fP9Xky E/q8Bfb9tiguXWGcQbjpHmgFycMUAwaAYIbyhjbY= Subject: FAILED: patch "[PATCH] ksmbd: prevent stale data from being written by SMB2 WRITE" failed to apply to 6.12-stable tree To: linkinjeon@kernel.org Cc: From: Date: Tue, 03 Nov 2026 11:18:51 +0100 Message-ID: <2026110350-activist-riot-545a@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b # git commit -s git send-email --to '' --in-reply-to '2026110350-activist-riot-545a@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Mon, 7 Sep 2026 13:35:51 +0900 Subject: [PATCH] ksmbd: prevent stale data from being written by SMB2 WRITE requests Initialize the compatibility byte in request buffers without zeroing the entire allocation. Keep the one-byte compatibility exception for SMB2 messages so valid zero-length WRITE requests remain compatible, and validate the data range in the WRITE handlers against the current compound request before accessing it. This prevents stale request-buffer data from being written to files or sent to IPC pipes. Fixes: 443d61d1fa9f ("ksmbd: allocate one more byte for implied bcc[0]") Cc: stable@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-32436 Signed-off-by: Namjae Jeon diff --git a/fs/smb/server/compress.c b/fs/smb/server/compress.c index 5162fb84c755..3fcb3e44302e 100644 --- a/fs/smb/server/compress.c +++ b/fs/smb/server/compress.c @@ -65,6 +65,7 @@ static int __ksmbd_decompress_request(struct ksmbd_conn *conn, return -ENOMEM; *(__be32 *)out = cpu_to_be32(out_size); + out[out_size + 4] = 0; rc = smb_compression_decompress(conn->compress_algorithm, conn->compress_chained, conn->compress_pattern, diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c index d211861ff86f..3f8cc4998da5 100644 --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -752,6 +752,7 @@ int ksmbd_conn_handler_loop(void *p) if (!conn->request_buf) break; + conn->request_buf[pdu_size + 4] = 0; memcpy(conn->request_buf, hdr_buf, sizeof(hdr_buf)); /* diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 18602a4759c0..c792ed5ebbd3 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -9276,23 +9276,25 @@ static noinline int smb2_write_pipe(struct ksmbd_work *work) int err = 0, ret = 0; char *data_buf; size_t length; + unsigned int data_offset, req_len; WORK_BUFFERS(work, req, rsp); length = le32_to_cpu(req->Length); id = req->VolatileFileId; + data_offset = le16_to_cpu(req->DataOffset); + req_len = smb2_current_req_len(work, &req->hdr); - if ((u64)le16_to_cpu(req->DataOffset) + length > - get_rfc1002_len(work->request_buf)) { - pr_err("invalid write data offset %u, smb_len %u\n", - le16_to_cpu(req->DataOffset), - get_rfc1002_len(work->request_buf)); + if (data_offset < offsetof(struct smb2_write_req, Buffer) || + data_offset > req_len || length > req_len - data_offset) { + pr_err("invalid write data offset %u, length %zu, req_len %u\n", + data_offset, length, req_len); err = -EINVAL; goto out; } data_buf = (char *)(((char *)&req->hdr.ProtocolId) + - le16_to_cpu(req->DataOffset)); + data_offset); rpc_resp = ksmbd_rpc_write(work->sess, id, data_buf, length); if (rpc_resp) { @@ -9579,14 +9581,21 @@ int smb2_write(struct ksmbd_work *work) writethrough = true; if (is_rdma_channel == false) { - if (le16_to_cpu(req->DataOffset) < - offsetof(struct smb2_write_req, Buffer)) { + unsigned int data_offset = le16_to_cpu(req->DataOffset); + unsigned int req_len = smb2_current_req_len(work, &req->hdr); + + if (data_offset < offsetof(struct smb2_write_req, Buffer) || + data_offset > req_len || + length > req_len - data_offset) { + ksmbd_debug(SMB, + "invalid write data offset %u, length %zu, req_len %u\n", + data_offset, length, req_len); err = -EINVAL; goto out; } data_buf = (char *)(((char *)&req->hdr.ProtocolId) + - le16_to_cpu(req->DataOffset)); + data_offset); ksmbd_debug(SMB, "filename %pD, offset %lld, len %zu\n", fp->filp, offset, length);