Ronnie reported invalid request buffer access in chained command when
inserting garbage value to NextCommand of compound request.
This patch add validation check to avoid this issue.
Cc: Ronnie Sahlberg <ronniesahlberg@xxxxxxxxx>
Cc: Ralph Böhme <slow@xxxxxxxxx>
Cc: Steve French <smfrench@xxxxxxxxx>
Reported-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
---
v2:
- fix integer overflow from work->next_smb2_rcv_hdr_off.
v3:
- check next command offset and at least header size of next pdu at
the same time.
fs/ksmbd/smb2pdu.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 4f11eb85bb6b..3d250e2539e6 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -466,6 +466,13 @@ bool is_chained_smb2_message(struct ksmbd_work *work)
hdr = ksmbd_req_buf_next(work);
if (le32_to_cpu(hdr->NextCommand) > 0) {
+ if ((u64)work->next_smb2_rcv_hdr_off + le32_to_cpu(hdr->NextCommand) + 64 >
+ get_rfc1002_len(work->request_buf)) {
+ pr_err("next command(%u) offset exceeds smb msg size\n",
+ le32_to_cpu(hdr->NextCommand));
+ return false;
+ }
+
ksmbd_debug(SMB, "got SMB2 chained command\n");
init_chained_smb2_rsp(work);
return true;
--
2.25.1
