ovl: make ioctl() safe

ovl_ioctl_set_flags() does a capability check using flags, but then the
real ioctl double-fetches flags and uses potentially different value.

The "Check the capability before cred override" comment misleading: user
can skip this check by presenting benign flags first and then overwriting
them to non-benign flags.

Just remove the cred override for now, hoping this doesn't cause a
regression.

The proper solution is to create a new setxflags i_op (patches are in the
works).

Xfstests don't show a regression.

Reported-by: Dmitry Vyukov <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
Reviewed-by: Amir Goldstein <[email protected]>
Fixes: dab5ca8fd9dd ("ovl: add lsattr/chattr support")
Cc: <[email protected]> # v4.19

0 files changed, 0 insertions, 0 deletions