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=1793701308; b=GmZ9o8QdsrC7den4nYsNgTjHnA+oQpcTLc2vT0700SNtQlvunKLpT08ZBWwxqXODjdE5 Dwx1SukQ4Ir0xWRR+jDamr3XjPeGxJNwWJi7ndDQTIm4vjJm9H17EpWg1hex+7obTZ5aY /G3Kar4gIEIT5fgfg4CuBQf/Myk4vGAKB2b+ZNoDjlrBplDQKrO7LAqmaqKuP/YrP4urt aj4haSV7dB+cUyyPCc/PIHlxFWFU0Y8by4t545AejYd2uAcF9LjJWM6rRtR8vOBkUdSFc ncOzpe/bmDaRmDnlIujePtdcFYU39+jROf9XrWAp7ipyJMRlo42LrlLmyIJgqEIYWlQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793701308; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=ymUfan6FhE4MA7QBX2KTqYc7mCgog8ThVpbP+wlntXw=; b=c+K+EaK2kXDmmpH3H/4hBXcArXZ0SrY1MAiPfVbQT1D1fV3gs3eul/ePQAwj1mQxmRkb /wkXd5MzcrGornyqGzxGaChFtfO0gobWjjIT3hBvlSFb/364R5cQSd5MaJ3AcJNNlgwee RYdQ+x7dwSfvKRCTocpZbpz+mNVJc6duVz6mT9sE5DGr3jP3epYciz97BNJsAH1HJPPKF vP/2A5QmXpBgAaYyxzM2FLlYYh7+X3KiIuDBBNJfT0degLr9z25nZQj6g3afyoHFmAyvq WR7b+6pye5wHJnczMv083acENltzxiqH+zJknXiEc2bZSBNLKU3F1oXbrQzwZkrMNzA== 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="qd/HCeNJ"; 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 57FB1606D803 for ; Tue, 3 Nov 2026 10:21:48 +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=qd/HCeNJ Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC28D1F0093A; Tue, 3 Nov 2026 10:21:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793701308; bh=ymUfan6FhE4MA7QBX2KTqYc7mCgog8ThVpbP+wlntXw=; h=Subject:To:Cc:From:Date; b=qd/HCeNJiyiDb2enetfOnUfQYRpKq7Dcz3CSO59w7PvNHx7PmE3GtLrL/Vze1SnaF rpv+zvIKEvlkM6DhtsjqmWztAF4I//kCb6FYXfAoqrVOCfhWTf14OOwAm/URLuvlnd 4fY9d3lZ90+Si5m8LpMnQR3Ok0k08XYjG3UzSmkY= Subject: FAILED: patch "[PATCH] ksmbd: fix out-of-bounds read when padding the final compound" failed to apply to 6.18-stable tree To: icb@fastmail.org,linkinjeon@kernel.org Cc: From: Date: Tue, 03 Nov 2026 11:21:40 +0100 Message-ID: <2026110340-sadness-alienable-ddc9@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x 714f27729121d59f103ca4dad7b0c2d1c125cd71 # git commit -s git send-email --to '' --in-reply-to '2026110340-sadness-alienable-ddc9@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 714f27729121d59f103ca4dad7b0c2d1c125cd71 Mon Sep 17 00:00:00 2001 From: Ian Bridges Date: Mon, 26 Oct 2026 20:40:21 -0500 Subject: [PATCH] ksmbd: fix out-of-bounds read when padding the final compound response Compound response handling pads the last response of a compound to an 8-byte boundary by growing the final iov and the RFC1002 length. smb2_allocate_rsp_buf() allocates exactly response_sz. A command can fill the response buffer to within 7 bytes of its end, for example a QUERY_INFO whose output is bounded only by the space left. The padding can then run past the allocation, and ksmbd_tcp_writev() reads those bytes when it sends the response. BUG: KASAN: slab-out-of-bounds in _copy_from_iter+0x744/0x10e0 Call Trace: _copy_from_iter+0x744/0x10e0 tcp_sendmsg_locked+0x2290/0x3f80 ksmbd_tcp_writev+0x10c7/0x1ab0 [ksmbd] Allocate room for the padding when the request is a compound, as smb2_read() and smb2_read_pipe() do for their payloads. response_sz is unchanged, so commands still fill only up to it, and kvzalloc() zeroes the padding. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Ian Bridges Signed-off-by: Namjae Jeon diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index db3a0500f9f3..b306bc6e21ee 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -969,7 +969,7 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) struct smb_version_values *vals = work->conn->vals; size_t small_sz = MAX_CIFS_SMALL_BUFFER_SIZE; size_t large_sz = small_sz + vals->max_trans_size; - size_t sz = small_sz; + size_t sz = small_sz, pad_sz = 0; int cmd = le16_to_cpu(hdr->Command); if (cmd == SMB2_IOCTL_HE || cmd == SMB2_QUERY_DIRECTORY_HE) @@ -995,10 +995,17 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) } /* allocate large response buf for chained commands */ - if (le32_to_cpu(hdr->NextCommand) > 0) + if (le32_to_cpu(hdr->NextCommand) > 0) { sz = large_sz; + /* + * is_chained_smb2_message() pads the last response of a + * compound to 8 bytes, which can take it past response_sz. + * Leave room for the padding. kvzalloc() zeroes it. + */ + pad_sz = ALIGN(sz - sizeof(__be32), 8) - (sz - sizeof(__be32)); + } - work->response_buf = kvzalloc(sz, KSMBD_DEFAULT_GFP); + work->response_buf = kvzalloc(sz + pad_sz, KSMBD_DEFAULT_GFP); if (!work->response_buf) return -ENOMEM;