c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal

A fix for commit b32dfe377102 ("c/r: prctl: add ability to set new
mm_struct::exe_file").

After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until
final mmput(), it never becomes NULL while task is alive.

We can check for other mapped files in mm instead of checking
mm->num_exe_file_vmas, and mark mm with flag MMF_EXE_FILE_CHANGED in
order to forbid second changing of mm->exe_file.

Signed-off-by: Konstantin Khlebnikov <[email protected]>
Reviewed-by: Cyrill Gorcunov <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Matt Helsley <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions