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 AE4873A05F2 for ; Mon, 7 Sep 2026 14:26:30 +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=1788791191; cv=none; b=ChvE7u/kN6Ik7KhKEsJK/y0xSpJzZU4dWohzHSgodqw49YO/7H6IF+rvEgpxGNqVJP0M8mowDdzUKzjO7UAHq1QFb4P/1VmSC4IwkYNgmfAqeYDC2/UMe0T6g0aPuBY6rWlU5gw/sdlTQqx4ifCkL6NDYve1jpZ0pGZcReJWaHk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788791191; c=relaxed/simple; bh=sxnrfzkSqfr0Q6pnGoFFh5wA4LhKUgVforNh3ZRUNp4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fMOKrYapoV8tGA6nhz0KWB2EV7k3eJUIVlJra396wvxxjUk9l+DNw6U4liBQDuWPAzIEaKUoVGkDxn1bvHWE0+PG6MwPhqUpdiAsTJ2iuMpWzE89P6cFBNM8/jF5NH0SA6r+9FDOkAvUCneRbQ9KSxOU/FFIxjA/3y/R7nnf1g8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fKgYvT03; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fKgYvT03" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C850D1F00A3A; Mon, 7 Sep 2026 14:26:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788791190; bh=20R7wGGdjpOjkXVoap/qVh1Jk2av9fHr7DipUh4xBMY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fKgYvT030XbUxRp/lTSK4fQgsw2qNBXqXmypm/16bfS5xf24t1rye7fW0gjwptHuX iokibxrVtvh82o0keWg32psbYNkVfOXm+PebCoLfzrtTs8/5pGEt/E8aqwvR4cGF3j jLAwCI0GPELq5Q/nUtjX8xSrwaUGE9BZzsRQnO9m7DIg5YEmdmJRYFkJRVuBuXX86S 70DaYVg8mUNLpez/o0q48l0wE87qxYGQWWZYeQJldwRD4IbmFCzqwDEWn6J6oB4NwA h+ZloqBsFxHk/U2TqmdIM/l9uPny/0i46ybv/jwzIPMo55uIvkb3vcceC89CKpr1fN hOo9EEvGWtNLg== From: Sasha Levin To: stable@vger.kernel.org Cc: Frank Sorenson , Shen Yongchao , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.10.y] smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2() Date: Mon, 7 Sep 2026 10:26:28 -0400 Message-ID: <20260907142628.3237483-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090304-drum-unbent-e6b0@gregkh> References: <2026090304-drum-unbent-e6b0@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Frank Sorenson [ Upstream commit 6343c1da561962688f203362d80d6a3bfa39fa1b ] coalesce_t2() computes data pointers directly from server-supplied DataOffset fields with no validation against buffer bounds: data_area_of_tgt = (char *)&pSMBt->hdr.Protocol + get_unaligned_le16(&pSMBt->t2_rsp.DataOffset); data_area_of_src = (char *)&pSMBs->hdr.Protocol + get_unaligned_le16(&pSMBs->t2_rsp.DataOffset); data_area_of_tgt += total_in_tgt; ... memcpy(data_area_of_tgt, data_area_of_src, total_in_src); A small DataOffset can push a pointer below the actual byte area, overwriting header fields; a large one can push it past the buffer end, causing out-of-bounds heap reads (source) or writes (target). The BCC overflow guard does not prevent this: BCC reflects how much data is present, while DataOffset controls where in the buffer it starts. The "validate target area" comment present since the function was first written in 2005 was a placeholder that was never implemented. Add lower- and upper-bound checks for both data pointers before the memcpy, and before any target header fields are modified. Fixes: e4eb295d38b5 ("[PATCH] cifs: Handle multiple response transact2 part 1 of 2") Cc: stable@vger.kernel.org Reported-by: Shen Yongchao Signed-off-by: Frank Sorenson Signed-off-by: Namjae Jeon Signed-off-by: Paulo Alcantara [ transplanted the bounds validation to coalesce_t2() in smb1ops.c due to code relocation ] Signed-off-by: Sasha Levin --- fs/cifs/smb1ops.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c index 80287c26cfac0..3b5427b17ff51 100644 --- a/fs/cifs/smb1ops.c +++ b/fs/cifs/smb1ops.c @@ -318,12 +318,31 @@ coalesce_t2(char *second_buf, struct smb_hdr *target_hdr) data_area_of_tgt = (char *)&pSMBt->hdr.Protocol + get_unaligned_le16(&pSMBt->t2_rsp.DataOffset); - /* validate target area */ data_area_of_src = (char *)&pSMBs->hdr.Protocol + get_unaligned_le16(&pSMBs->t2_rsp.DataOffset); data_area_of_tgt += total_in_tgt; + /* + * DataOffset fields are server-supplied and not validated against + * buffer bounds; check both data pointers before mutating the + * target header. + */ + if (data_area_of_tgt < (char *)target_hdr + + sizeof(struct smb_t2_rsp) + sizeof(__le16) || + data_area_of_tgt + total_in_src > + (char *)target_hdr + CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) { + cifs_dbg(VFS, "%s: target data area out of bounds\n", __func__); + return -EPROTO; + } + if (data_area_of_src < second_buf + + sizeof(struct smb_t2_rsp) + sizeof(__le16) || + data_area_of_src + total_in_src > + second_buf + smbCalcSize((struct smb_hdr *)second_buf)) { + cifs_dbg(VFS, "%s: secondary data area out of bounds\n", __func__); + return -EPROTO; + } + total_in_tgt += total_in_src; /* is the result too big for the field? */ if (total_in_tgt > USHRT_MAX) { -- 2.53.0