mm: mmap: Fix general protection fault in unlink_file_vma()

Quoted 9 lines · On Thu, 8 Oct 2020 07:17:18 +0000 linmiaohe <[email protected]> wrote:

Quoted 7 lines · Andrew Morton

Quoted 1 line · On Wed, 16 Sep 2020 05:07:33 -0400 Miaohe Lin <[email protected]> wrote:

The syzbot reported the below general protection fault:

is this using the correct file? I think it is, but please do check.

Quoted 6 lines

Many thanks for your reply.

Yes, I think so too. We do deny_write_access and mapping_map_writable on @file, so we should undo all of this on @file. Since @file is unchanged over the second vma_merge() time, we'are using the correct @file to undo our temporary denial count.

But how should I check this explicitly ? I can't find out a way to do this. Could you please figure it out for me?

I meant "please check (review) the code as it now is", not "please add a check" ;)