Hello Paulo Alcantara,
The patch c877ce47e137: "cifs: reduce roundtrips on create/qinfo
requests" from Dec 12, 2022, leads to the following Smatch static
checker warning:
fs/cifs/smb2ops.c:865 smb2_is_path_accessible()
warn: variable dereferenced before check 'cifs_sb' (see line 834)
fs/cifs/smb2ops.c
811 static int
812 smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
813 struct cifs_sb_info *cifs_sb, const char *full_path)
814 {
815 __le16 *utf16_path;
816 __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
817 int err_buftype = CIFS_NO_BUFFER;
818 struct cifs_open_parms oparms;
819 struct kvec err_iov = {};
820 struct cifs_fid fid;
821 struct cached_fid *cfid;
822 bool islink;
823 int rc, rc2;
824
825 rc = open_cached_dir(xid, tcon, full_path, cifs_sb, true, &cfid);
826 if (!rc) {
827 if (cfid->has_lease) {
828 close_cached_dir(cfid);
829 return 0;
830 }
831 close_cached_dir(cfid);
832 }
833
834 utf16_path = cifs_convert_path_to_utf16(full_path, cifs_sb);
^^^^^^^
Unchecked dereference inside the function.
835 if (!utf16_path)
836 return -ENOMEM;
837
838 oparms = (struct cifs_open_parms) {
839 .tcon = tcon,
840 .path = full_path,
841 .desired_access = FILE_READ_ATTRIBUTES,
842 .disposition = FILE_OPEN,
843 .create_options = cifs_create_options(cifs_sb, 0),
844 .fid = &fid,
845 };
846
847 rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
848 &err_iov, &err_buftype);
849 if (rc) {
850 struct smb2_hdr *hdr = err_iov.iov_base;
851
852 if (unlikely(!hdr || err_buftype == CIFS_NO_BUFFER))
853 goto out;
854
855 if (rc != -EREMOTE && hdr->Status == STATUS_OBJECT_NAME_INVALID) {
856 rc2 = cifs_inval_name_dfs_link_error(xid, tcon, cifs_sb,
857 full_path, &islink);
858 if (rc2) {
859 rc = rc2;
860 goto out;
861 }
862 if (islink)
863 rc = -EREMOTE;
864 }
--> 865 if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&
^^^^^^^
No point in checking after a dereference.
866 (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))
867 rc = -EOPNOTSUPP;
868 goto out;
869 }
870
871 rc = SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
872
873 out:
874 free_rsp_buf(err_buftype, err_iov.iov_base);
875 kfree(utf16_path);
876 return rc;
877 }
regards,
dan carpenter
