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Groups > linux.kernel > #1681666
| From | Linus Torvalds <torvalds@linux-foundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] mm: larger stack guard gap, between vmas |
| Date | 2017-07-05 19:20 +0200 |
| Message-ID | <tZW82-JF-17@gated-at.bofh.it> (permalink) |
| References | (6 earlier) <tZFAe-6E3-3@gated-at.bofh.it> <tZRBp-6aJ-27@gated-at.bofh.it> <tZTtw-7s2-19@gated-at.bofh.it> <tZUpB-83i-45@gated-at.bofh.it> <tZVOF-nA-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Jul 5, 2017 at 9:58 AM, Ben Hutchings <ben@decadent.org.uk> wrote:
>
> I ended up with the following two patches, which seem to deal with
> both the Java and Rust regressions. These don't touch the
> stack-grows-up paths at all because Rust doesn't run on those
> architectures and the Java weirdness is i386-specific.
>
> They definitely need longer commit messages and comments, but aside
> from that do these look reasonable?
I thin kthey both look reasonable, but I think we might still want to
massage things a bit (cutting down the quoting to a minimum, hopefully
leaving enough context to still make sense):
> Subject: [1/2] mmap: Skip a single VM_NONE mapping when checking the stack gap
>
> prev = vma->vm_prev;
> + if (prev && !(prev->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
> + prev = prev->vm_prev;
> if (prev && prev->vm_end > gap_addr) {
Do we just want to ignore the user-supplied guard mapping, or do we
want to say "if the user does a guard mapping, we use that *instead*
of our stack gap"?
IOW, instead of "prev = prev->vm_prev;" and continuing, maybe we want
to just return "ok".
> Subject: [2/2] mmap: Avoid mapping anywhere within the full stack extent if finite
This is good thinking, but no, I don't think the "if finite" is right.
I've seen people use "really big values" as replacement for
RLIM_INIFITY, for various reasons.
We've had huge confusion about RLIM_INFINITY over the years - look for
things like COMPAT_RLIM_OLD_INFINITY to see the kinds of confusions
we've had.
Some people just use MAX_LONG etc, which is *not* the same as
RLIM_INFINITY, but in practice ends up doing the same thing. Yadda
yadda.
So I'm personally leery of checking and depending on "exactly
RLIM_INIFITY", because I've seen it go wrong so many times.
And I think your second patch breaks that "use a really large value to
approximate infinity" case that definitely has existed as a pattern.
Linus
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Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-04 02:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-04 02:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 10:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 11:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 11:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 12:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-04 13:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 14:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 14:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-04 14:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 14:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ximin Luo <infinity0@debian.org> - 2017-07-04 16:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 16:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 18:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 19:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-04 20:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-04 20:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 21:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 20:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-04 18:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas John Haxby <john.haxby@oracle.com> - 2017-07-04 18:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 19:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 14:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-04 19:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 14:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 01:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 01:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 08:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 10:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 10:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 11:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 14:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 16:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 16:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 18:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-06 09:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 14:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 16:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 17:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 18:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 19:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-05 19:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 19:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 19:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-06 01:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-06 02:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-06 10:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-06 12:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-05 18:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 18:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-05 19:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-05 21:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 22:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@amacapital.net> - 2017-07-05 23:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Ben Hutchings <ben@decadent.org.uk> - 2017-07-06 02:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-06 02:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Kees Cook <keescook@chromium.org> - 2017-07-06 02:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-06 02:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-06 02:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-06 02:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-06 02:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Kees Cook <keescook@chromium.org> - 2017-07-06 04:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-06 07:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Kevin Easton <kevin@guarana.org> - 2017-07-06 07:40 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 18:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 21:10 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Willy Tarreau <w@1wt.eu> - 2017-07-05 21:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 21:30 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-05 21:20 +0200
Re: [vs-plain] Re: [PATCH] mm: larger stack guard gap, between vmas "kseifried@redhat.com" <kseifried@redhat.com> - 2017-07-05 03:20 +0200
Re: [vs-plain] Re: [PATCH] mm: larger stack guard gap, between vmas Solar Designer <solar@openwall.com> - 2017-07-05 16:20 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 12:50 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Michal Hocko <mhocko@kernel.org> - 2017-07-04 13:00 +0200
Re: [PATCH] mm: larger stack guard gap, between vmas Andy Lutomirski <luto@kernel.org> - 2017-07-04 02:30 +0200
Re: [vs-plain] Re: [PATCH] mm: larger stack guard gap, between vmas John Haxby <john.haxby@oracle.com> - 2017-07-04 14:30 +0200
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