Messages in this thread | | | Date | Sun, 12 Oct 2003 04:53:32 -0700 | From | Andrew Morton <> | Subject | Re: [RFC] invalidate_mmap_range() misses remap_file_pages()-affected targets |
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William Lee Irwin III <wli@holomorphy.com> wrote: > > invalidate_mmap_range(), and hence vmtruncate(), can miss its targets > due to remap_file_pages() disturbing the former invariant of file > offsets only being mapped within vmas tagged as mapping file offset > ranges containing them.
I was going to just not bother about this wart. After all, we get to write the standard on remap_file_pages(), and we can say "the truncate-causes-SIGBUS thing doesn't work". After all, it is not very useful.
But I wonder if this effect could be used maliciously. Say, user A has read-only access to user B's file, and uses that access to set up a nonlinear mapping thereby causing user B's truncate to not behave correctly. But this example is OK, isn't it? User A will just receive an anonymous page for his troubles.
Can you think of any stability or security scenario which says that we _should_ implement the conventional truncate behaviour?
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