[PATCH 5.15 04/98] ksmbd: check invalid FileOffset and BeyondFinalZero in FSCTL_ZERO_DATA

Greg Kroah-Hartman
2022-07-05T12:24:28Z

From: Namjae Jeon <linkinjeon@kernel.org>

commit b5e5f9dfc915ff05b41dff56181e1dae101712bd upstream.

FileOffset should not be greater than BeyondFinalZero in FSCTL_ZERO_DATA.
And don't call ksmbd_vfs_zero_data() if length is zero.

Cc: stable@vger.kernel.org
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ksmbd/smb2pdu.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)

--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -7684,7 +7684,7 @@ int smb2_ioctl(struct ksmbd_work *work)
{
struct file_zero_data_information *zero_data;
struct ksmbd_file *fp;
- loff_t off, len;
+ loff_t off, len, bfz;

if (!test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
ksmbd_debug(SMB,
@@ -7701,19 +7701,26 @@ int smb2_ioctl(struct ksmbd_work *work)
zero_data =
(struct file_zero_data_information *)&req->Buffer[0];

- fp = ksmbd_lookup_fd_fast(work, id);
- if (!fp) {
- ret = -ENOENT;
+ off = le64_to_cpu(zero_data->FileOffset);
+ bfz = le64_to_cpu(zero_data->BeyondFinalZero);
+ if (off > bfz) {
+ ret = -EINVAL;
goto out;
}

- off = le64_to_cpu(zero_data->FileOffset);
- len = le64_to_cpu(zero_data->BeyondFinalZero) - off;
-
- ret = ksmbd_vfs_zero_data(work, fp, off, len);
- ksmbd_fd_put(work, fp);
- if (ret < 0)
- goto out;
+ len = bfz - off;
+ if (len) {
+ fp = ksmbd_lookup_fd_fast(work, id);
+ if (!fp) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ ret = ksmbd_vfs_zero_data(work, fp, off, len);
+ ksmbd_fd_put(work, fp);
+ if (ret < 0)
+ goto out;
+ }
break;
}