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=1793831917; b=iXEPkaxPu5tciEd97vEr+QlPfs5FDIAEt6onjcvbCVvHFBT35Sdt4Pe1XHKWMoM443wh hl7kwEz37CbZ6exB+GYbpuUEHsScCJVgP08Rx8Y9Ec7fZXV0boJuUQnqj8l878K+d6zqy gRj34OczYtsD0ruBOcp5rx3Y7NSN8l8+pXeCow0yhhMH6N/Oi66pVuMXlN3eUL36USoYS WyC74UkR5DUH9dHIlQfEATGbvT/zXdPfK4Sg9WBiMzw3k9Q9HFQYpbu+taXFDJ7APfK2A sk0UzR8H2LK4WRVshtUMnEIf4rGSjZzXDGrAbYbPJywZWulncHmRd5EUlS4iu7m+MyA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831917; 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=3IpThQ4kY9a3CoV0nDaJ007tdBDx5t5HB+Ek+TShN0k=; b=A4y/HZkuCDzvhP/pLEQ0i0RRPa5yxR9SvDAkH8wuQ9HAaO2Er/yQtxbA0lJHV6b2uq8v QMNOo6tDcMdbIwrUDcfPdMaeONf6558iwDz/s0Zl6ThK/koutL2d6NqkRXi7J80D8lcwy YeK+eio+YIGu2iy8Qo9dJb9mLhMJ0C7ZYWeL8O4dIvSdiFjWj01Wo3zNfSsCIb/RMsKWq 3oKxlQD7p6zZrXrXLUFdIvCd7YFtE5fXS5kQebk38Z19caAI0L8/rpLx5QZR/c075foeu Q9RQTE0KCoICKPVTzgttl8AQSfTW2L66oGi52qz1QW3FZD1QKX2VxTq6aPyOrMK7New== 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=gXDt2jmX; 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 B5250606A86E; Wed, 4 Nov 2026 22:38:36 +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=gXDt2jmX Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51CED1F00919; Wed, 4 Nov 2026 22:38:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831916; bh=3IpThQ4kY9a3CoV0nDaJ007tdBDx5t5HB+Ek+TShN0k=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gXDt2jmXo+NEcJkvQrGbsEuZKQjwu4HtHX2ep11u/XfLqkAQ0Bm2JibIqZFest8sB jSPk5XtdWu/DZgIJnLilfe+yqsPupvWTWkBctNLpH4aAbhJZE2PiJk57tm/dF0TOWq kANEkGN+yhjnsapOuj6BkRIjeFPxH4m5ZeyAo5X4= 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 6.18 0992/1005] ksmbd: fix out-of-bounds read when padding the final compound response Date: Wed, 4 Nov 2026 16:12:05 -0500 Message-ID: <20261104211110.823433885@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-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 to retain work->conn->vals->max_trans_size instead of vals->max_trans_size. ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/smb2pdu.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -539,7 +539,7 @@ int smb2_allocate_rsp_buf(struct ksmbd_w 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) @@ -561,10 +561,17 @@ int smb2_allocate_rsp_buf(struct ksmbd_w } /* 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;