proc: make check_mem_permission() return an mm_struct on success

This change allows us to take advantage of access_remote_vm(), which in turn
eliminates a security issue with the mem_write() implementation.

The previous implementation of mem_write() was insecure since the target task
could exec a setuid-root binary between the permission check and the actual
write.  Holding a reference to the target mm_struct eliminates this
vulnerability.

Signed-off-by: Stephen Wilson <[email protected]>
Signed-off-by: Al Viro <[email protected]>

0 files changed, 0 insertions, 0 deletions