On Wed, Mar 07, 2018 at 09:57:24AM +0200, Nikolay Borisov wrote: > From: Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx> > > When changing a file's acl mask, btrfs_set_acl() will first set the > group bits of i_mode to the value of the mask, and only then set the > actual extended attribute representing the new acl. > > If the second part fails (due to lack of space, for example) and the > file had no acl attribute to begin with, the system will from now on > assume that the mask permission bits are actual group permission bits, > potentially granting access to the wrong users. > > Prevent this by restoring the original mode bits if __btrfs_set_acl > fails. > > Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx> > Reviewed-by: David Sterba <dsterba@xxxxxxxx> > Signed-off-by: David Sterba <dsterba@xxxxxxxx> > Acked-by: Nikolay Borisov <nborisov@xxxxxxxx> > Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx> > --- > fs/btrfs/acl.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) Shouldn't this also be added to 4.9.y? thanks, greg k-h