[PATCH] ksmbd: fix potencial 32bit overflow from data area check in smb2_write

Namjae Jeon
2021-10-12T01:20:20Z

DataOffset and Length validation can be potencial 32bit overflow.
This patch fix it.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
fs/ksmbd/smb2pdu.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 79b296abe04e..7b4689f2df49 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -6197,8 +6197,7 @@ static noinline int smb2_write_pipe(struct ksmbd_work *work)
(offsetof(struct smb2_write_req, Buffer) - 4)) {
data_buf = (char *)&req->Buffer[0];
} else {
- if ((le16_to_cpu(req->DataOffset) > get_rfc1002_len(req)) ||
- (le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req))) {
+ if ((u64)le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req)) {
pr_err("invalid write data offset %u, smb_len %u\n",
le16_to_cpu(req->DataOffset),
get_rfc1002_len(req));
@@ -6356,8 +6355,7 @@ int smb2_write(struct ksmbd_work *work)
(offsetof(struct smb2_write_req, Buffer) - 4)) {
data_buf = (char *)&req->Buffer[0];
} else {
- if ((le16_to_cpu(req->DataOffset) > get_rfc1002_len(req)) ||
- (le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req))) {
+ if ((u64)le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req)) {
pr_err("invalid write data offset %u, smb_len %u\n",
le16_to_cpu(req->DataOffset),
get_rfc1002_len(req));
--
2.25.1