[PATCH 4.9 48/59] cifs: read overflow in is_valid_oplock_break()

Greg Kroah-Hartman
2018-10-08T18:41:03Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 097f5863b1a0c9901f180bbd56ae7d630655faaa ]

We need to verify that the "data_offset" is within bounds.

Reported-by: Dr Silvio Cesare of InfoSect <silvio.cesare@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/misc.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -406,9 +406,17 @@ is_valid_oplock_break(char *buffer, stru
(struct smb_com_transaction_change_notify_rsp *)buf;
struct file_notify_information *pnotify;
__u32 data_offset = 0;
+ size_t len = srv->total_read - sizeof(pSMBr->hdr.smb_buf_length);
+
if (get_bcc(buf) > sizeof(struct file_notify_information)) {
data_offset = le32_to_cpu(pSMBr->DataOffset);

+ if (data_offset >
+ len - sizeof(struct file_notify_information)) {
+ cifs_dbg(FYI, "invalid data_offset %u\n",
+ data_offset);
+ return true;
+ }
pnotify = (struct file_notify_information *)
((char *)&pSMBr->hdr.Protocol + data_offset);
cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",