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=1793748486; b=JzItSbI0Kr1ny2XR66gKoUK+9MDGkEHbmtkt+cD/bPOBdZY1oiJI8POx/wGnfVed1Q5w HsaU5IczP/Wz4MQCoHgue4LKnnBCEeQYH9LKRDpQWtqD/UVsX+Km8WFc5fe2GxshGFg9y Qjo23WR+6t+Bx+K5vVeVXuAXk9lbvJprXD8NBjQ7q6kPDYGFo50eCmeyDwPRnVWeF5ypL eyTBESVkBpB/gjUVrMJGsQFH5SZkBWSvSwYzXAXzA6i7HFAHDbHBs5o0qoQef6uztj3f/ NV49Xq9aU9uUYzUQA4NDAHrZVOXhIGrTqnrDfFt3S4lLcHz/RLqqhgSkN/yPrGoU5vg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793748486; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ho/+1NPALtJlojAFcl626txMYj4Z0uTanNT0kkQ3VCc=; b=lXF3fGCwj5GBkwJHSfOkYQLGldVjD3X8wDsbmwZfiVBLBPJhI+fPm2hpfYdjdGDdFtBe ytoiea6/CRfYjPmxbuMrQGfWfra3PHheaq7/0DT6IBf0u8dw5B2hoAve9/yCaD/e5tif8 kYIekSAlzmkhwzpFlTVJ8Z+A/fk+yZfegIqdSZR2Fl255+iPG6LHu6as8NqxFMcybo9fL /svmcb7NttzAxdDXOLws5E6KDm7gGY8wJyfnwASE0ta259I3l49Q6B1ozryu7NFYq9P7u RTn5eCO0lG2undPzv1MURpJF2zQaM0HFmxLFNUrWSORP+j2HP3N2G1YP6DznXV/r6YA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nWKvwSxG; 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 72735606A326 for ; Tue, 3 Nov 2026 23:28:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nWKvwSxG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 913C41F000C1; Tue, 3 Nov 2026 23:28:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793748486; bh=ho/+1NPALtJlojAFcl626txMYj4Z0uTanNT0kkQ3VCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nWKvwSxGEPscp8EtbHyJj3OUTQ49o56E6u8/dNcKn/w5ysgdbsAuSPvL2bytWKJ/t t75Gqym8Z3T/XokJWA5axAAXzRDltNdwzgiWcx8E1HSdW6MbwSQAepfpRWa2eLREA8 rTOpOTG9ZOGoPRV6yKABsCOA1OzUUc2+HhwajQrMX+AEZVn4wisONfssY4YB35bLg/ B29YEDz8T0vQkXrkBpNwVVTVnE4C0BPefSyVFeklRjCvsFD5zYgPl/SBKd2kDBetaU 4mtgnfNbcBJACfpC1C1tkVlPSo0PD1pNxMaQH8MQEvC8Q25/jdgRFE8l7M5QWx7zSh cNoLEZMLyPBxQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Namjae Jeon , zdi-disclosures@trendmicro.com, Sasha Levin Subject: [PATCH 5.15.y] ksmbd: prevent stale data from being written by SMB2 WRITE requests Date: Tue, 3 Nov 2026 18:28:04 -0500 Message-ID: <20261103232717.1549133-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110352-stung-radiation-169e@gregkh> References: <2026110352-stung-radiation-169e@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-Transfer-Encoding: 8bit From: Namjae Jeon [ Upstream commit bc0e0f5ac1d7b044d403f859406b4b66d4b1ce9b ] 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 [ sashal: inlined smb2_current_req_len() calculations at both call sites because the helper is absent ] Signed-off-by: Sasha Levin --- fs/ksmbd/connection.c | 1 + fs/ksmbd/smb2pdu.c | 34 +++++++++++++++++++++++++--------- 2 files changed, 26 insertions(+), 9 deletions(-) diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c index 65dd05290c9ba..9dd02322275fc 100644 --- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/connection.c @@ -399,6 +399,7 @@ 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/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 4c42205fe5261..b321f13bf8ee5 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -6552,23 +6552,28 @@ 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 = le32_to_cpu(req->hdr.NextCommand); + if (!req_len) + req_len = get_rfc1002_len(work->request_buf) - + work->next_smb2_rcv_hdr_off; - 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) { @@ -6719,14 +6724,25 @@ 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 = le32_to_cpu(req->hdr.NextCommand); + + if (!req_len) + req_len = get_rfc1002_len(work->request_buf) - + work->next_smb2_rcv_hdr_off; + + 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); -- 2.53.0