ksmbd: fix posix_acls and acls dereferencing possible ERR_PTR()

[ Upstream commit 2593357 ]

Dan reported the following error message:

fs/smb/server/smbacl.c:1296 smb_check_perm_dacl()
    error: 'posix_acls' dereferencing possible ERR_PTR()
fs/smb/server/vfs.c:1323 ksmbd_vfs_make_xattr_posix_acl()
    error: 'posix_acls' dereferencing possible ERR_PTR()
fs/smb/server/vfs.c:1830 ksmbd_vfs_inherit_posix_acl()
    error: 'acls' dereferencing possible ERR_PTR()

__get_acl() returns a mix of error pointers and NULL. This change it
with IS_ERR_OR_NULL().

Fixes: e2f3448 ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/smb/server/smbacl.c

@@ -1313,7 +1313,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 
 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL)) {
 		posix_acls = get_acl(d_inode(path->dentry), ACL_TYPE_ACCESS);
-		if (posix_acls && !found) {
+		if (!IS_ERR_OR_NULL(posix_acls) && !found) {
 			unsigned int id = -1;
 
 			pa_entry = posix_acls->a_entries;
@@ -1337,7 +1337,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 				}
 			}
 		}
-		if (posix_acls)
+		if (!IS_ERR_OR_NULL(posix_acls))
 			posix_acl_release(posix_acls);
 	}
 

fs/smb/server/vfs.c

@@ -1322,7 +1322,7 @@ static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct user_namespac
 		return NULL;
 
 	posix_acls = get_acl(inode, acl_type);
-	if (!posix_acls)
+	if (IS_ERR_OR_NULL(posix_acls))
 		return NULL;
 
 	smb_acl = kzalloc(sizeof(struct xattr_smb_acl) +
@@ -1830,7 +1830,7 @@ int ksmbd_vfs_inherit_posix_acl(struct user_namespace *user_ns,
 		return -EOPNOTSUPP;
 
 	acls = get_acl(parent_inode, ACL_TYPE_DEFAULT);
-	if (!acls)
+	if (IS_ERR_OR_NULL(acls))
 		return -ENOENT;
 	pace = acls->a_entries;