Le 23/04/2019 à 15:34, Thomas Gleixner a écrit :
On Tue, 23 Apr 2019, Laurent Dufour wrote:
Le 20/04/2019 à 12:31, Michael Ellerman a écrit :
Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:
Aside of that the powerpc variant looks suspicious:
static inline void arch_unmap(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
mm->context.vdso_base = 0;
}
Shouldn't that be:
if (start >= mm->context.vdso_base && mm->context.vdso_base < end)
Hmm?
Yeah looks pretty suspicious. I'll follow-up with Laurent who wrote it.
Thanks for spotting it!
I've to admit that I had to read that code carefully before answering.
There are 2 assumptions here:
1. 'start' and 'end' are page aligned (this is guaranteed by __do_munmap().
2. the VDSO is 1 page (this is guaranteed by the union vdso_data_store on
powerpc).
The idea is to handle a munmap() call surrounding the VDSO area:
| VDSO |
^start ^end
This is covered by this test, as the munmap() matching the exact boundaries of
the VDSO is handled too.
Am I missing something ?
Well if this is the intention, then you missed to add a comment explaining it :)
Thanks,
tglx
You're right, and I was thinking the same when I read that code this
morning ;)
I'll propose a patch to a add an explicit comment.
Thanks,
Laurent.
