[PATCH 2/8] smb/server: fix potential null-ptr-deref of lease_ctx_info in smb2_open()

[chenxiaosong@xxxxxxxxxxxxxxxxxxx]

From: ChenXiaoSong <chenxiaosong@xxxxxxxxxx>

null-ptr-deref will occur when (req_op_level == SMB2_OPLOCK_LEVEL_LEASE)
and parse_lease_state() return NULL.

Fix this by returning error pointer on parse_lease_state() and checking
error.

Signed-off-by: ChenXiaoSong <chenxiaosong@xxxxxxxxxxxxxxxx>
---
 fs/smb/server/oplock.c  | 11 +++++++----
 fs/smb/server/smb2pdu.c | 17 ++++++++++++-----
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c
index a8f52c4ebbda..e8591686a037 100644
--- a/fs/smb/server/oplock.c
+++ b/fs/smb/server/oplock.c
@@ -1510,7 +1510,8 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
  * parse_lease_state() - parse lease context containted in file open request
  * @open_req:	buffer containing smb2 file open(create) request
  *
- * Return:  oplock state, -ENOENT if create lease context not found
+ * Return: allocated lease context object on success, otherwise error pointer.
+ * 	   -ENOENT pointer if create lease context not found.
  */
 struct lease_ctx_info *parse_lease_state(void *open_req)
 {
@@ -1519,12 +1520,14 @@ struct lease_ctx_info *parse_lease_state(void *open_req)
 	struct lease_ctx_info *lreq;
 
 	cc = smb2_find_context_vals(req, SMB2_CREATE_REQUEST_LEASE, 4);
-	if (IS_ERR_OR_NULL(cc))
-		return NULL;
+	if (!cc)
+		return ERR_PTR(-ENOENT);
+	if (IS_ERR(cc))
+		return ERR_CAST(cc);
 
 	lreq = kzalloc(sizeof(struct lease_ctx_info), GFP_KERNEL);
 	if (!lreq)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	if (sizeof(struct lease_context_v2) == le32_to_cpu(cc->DataLength)) {
 		struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index d8a827e0dced..119c1ba5f255 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2767,8 +2767,9 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				}
 			}
 
-			if (((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
-			     req_op_level == SMB2_OPLOCK_LEVEL_BATCH)) {
+			if ((!IS_ERR_OR_NULL(lc) > 0 &&
+			     (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
+			    req_op_level == SMB2_OPLOCK_LEVEL_BATCH) {
 				dh_info->CreateGuid =
 					durable_v2_blob->CreateGuid;
 				dh_info->persistent =
@@ -2788,8 +2789,9 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				goto out;
 			}
 
-			if (((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
-			     req_op_level == SMB2_OPLOCK_LEVEL_BATCH)) {
+			if ((!IS_ERR_OR_NULL(lc) &&
+			     (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
+			    req_op_level == SMB2_OPLOCK_LEVEL_BATCH) {
 				ksmbd_debug(SMB, "Request for durable open\n");
 				dh_info->type = dh_idx;
 			}
@@ -2935,8 +2937,13 @@ int smb2_open(struct ksmbd_work *work)
 			ksmbd_put_durable_fd(fp);
 			goto reconnected_fp;
 		}
-	} else if (req_op_level == SMB2_OPLOCK_LEVEL_LEASE)
+	} else if (req_op_level == SMB2_OPLOCK_LEVEL_LEASE) {
 		lc = parse_lease_state(req);
+		if (IS_ERR(lc)) {
+			rc = PTR_ERR(lc);
+			goto err_out2;
+		}
+	}
 
 	if (le32_to_cpu(req->ImpersonationLevel) > le32_to_cpu(IL_DELEGATE)) {
 		pr_err("Invalid impersonationlevel : 0x%x\n",
-- 
2.34.1