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cifs: properly invalidate cached root handle when closing it

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Cached root file was not being completely invalidated sometimes.

Reproducing:
- With a DFS share with 2 targets, one disabled and one enabled
- start some I/O on the mount
  # while true; do ls /mnt/dfs; done
- at the same time, disable the enabled target and enable the disabled
  one
- wait for DFS cache to expire
- on reconnect, the previous cached root handle should be invalid, but
  open_cached_dir_by_dentry() will still try to use it, but throws a
  use-after-free warning (kref_get())

Make smb2_close_cached_fid() invalidate all fields every time, but only
send an SMB2_close() when the entry is still valid.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Enzo Matsumiya 2021-09-09 18:46:45 -03:00 committed by Steve French
parent 8d014f5fe9
commit 9351590f51
1 changed files with 13 additions and 7 deletions
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20
fs/cifs/smb2ops.c
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@ -689,13 +689,19 @@ smb2_close_cached_fid(struct kref *ref)
cifs_dbg(FYI, "clear cached root file handle\n");
SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
cfid->fid->volatile_fid);
cfid->is_valid = false;
cfid->file_all_info_is_valid = false;
cfid->has_lease = false;
if (cfid->dentry) {
dput(cfid->dentry);
cfid->dentry = NULL;
}
}
/*
* We only check validity above to send SMB2_close,
* but we still need to invalidate these entries
* when this function is called
*/
cfid->is_valid = false;
cfid->file_all_info_is_valid = false;
cfid->has_lease = false;
if (cfid->dentry) {
dput(cfid->dentry);
cfid->dentry = NULL;
}
}