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=1794061826; b=bINBp7cao8/GqnKSoiaJg3FW8RHTx/PN6k+HQEOesXQF1EOD9Wn8ZYbmpTxZAbcSHP7A bAwfMZv9H17/Lm2UYhgGjfaHNiznymhiN3XBNemkd5m3ASWcvZuV11Ewrr4mYCQKYJqc6 YH6qpOvFneKvMdH3cLwt4LWztE904ePa1tEjx4RNgWghKpXpk7gPREDWsEsBsHxWhjx8s Wi8bmvVioCRhkHA7kwwHl06aQAAhkXCXGi3Pe9zNcCCxWPibDMNdSEF2RgVNCNQRjSTrm 9OdOHsXrFkIan8PyoQqNx5wQhtgbrQoFVjbUEpBbhzQue5z+VOs+GhfPG1ah7ZlgfXA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061826; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=rWODjUy9+ZTPwi6uQERUjjcRoG7en8gclEJcf3YO5ks=; b=tL4Qi+rTqKobMY44mTkqAqzbTYqh0XbclVMIE6vw0c+QA+tV4knV7xyhRxiAdpsQdryw uoS+Fm2kFJkHdnzVjPjfYwDLqTBC3k0puME0mXl3PgEwICBO7zKwCd3MAZA7jUPqwbuPU 4uH09Xlpe6Ysbgx4/x43fvgnMu7FYoVKBZtaGZC4YB3TglsUCy0CNjzz/AOflNFJsUCpY /qQT+OmmfmiCSGAHsb0MdC2xtFnf9DreG6FLh0w2hgz/PCzc2hmYO6hY8/clKS7tJSc+I hlEvQlL5e8yVWlpDn9MkozzlkMqzHPOXpCJ1W/zNeZdATXsxllD9q1Vy+cKK7eWBDwA== 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=QNYEEVbt; 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 BB44A606A326; Sat, 7 Nov 2026 14:30:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=QNYEEVbt Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69CEE1F008A1; Sat, 7 Nov 2026 14:30:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061825; bh=rWODjUy9+ZTPwi6uQERUjjcRoG7en8gclEJcf3YO5ks=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QNYEEVbtZllkIOvRQI49fgIhbhcplVFXeW90M2YAIDZiXyyhFICg4dXRneF/OX8Y7 hjNRCkOOG4Bfqkw0MP4pZ7xgM5i9i81oFQCsMh+R13dVoRzN7g0wj40G6ejTyUbSqm EAiwVLtF4ytg+BN38voPaBeFyBmFROnmy16S4QIU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ian Bridges , Namjae Jeon , Sasha Levin Subject: [PATCH 6.12 0848/1536] ksmbd: fix out-of-bounds read when padding the final compound response Date: Sat, 7 Nov 2026 08:47:44 -0500 Message-ID: <20261107135021.366518395@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Bridges [ Upstream commit 714f27729121d59f103ca4dad7b0c2d1c125cd71 ] 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 [ sashal: adjusted context for direct work->conn->vals access instead of a local vals variable ] Signed-off-by: Sasha Levin --- fs/smb/server/smb2pdu.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 0ecec7bf31119..d892fd736785f 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -538,7 +538,7 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work) struct smb2_hdr *hdr = smb_get_msg(work->request_buf); size_t small_sz = MAX_CIFS_SMALL_BUFFER_SIZE; size_t large_sz = small_sz + work->conn->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) @@ -560,10 +560,17 @@ 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; -- 2.53.0