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Groups > linux.kernel > #1681660
| From | Ben Hutchings <ben@decadent.org.uk> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] mm: larger stack guard gap, between vmas |
| Date | 2017-07-05 19:00 +0200 |
| Message-ID | <tZVOF-nA-13@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <tZF7c-6uZ-9@gated-at.bofh.it> <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> |
| Organization | linux.* mail to news gateway |
[Multipart message — attachments visible in raw view] - view raw
On Wed, Jul 05, 2017 at 04:25:00PM +0100, Ben Hutchings wrote:
[...]
> Soemthing I noticed is that Java doesn't immediately use MAP_FIXED.
> Look at os::pd_attempt_reserve_memory_at(). If the first, hinted,
> mmap() doesn't return the hinted address it then attempts to allocate
> huge areas (I'm not sure how intentional this is) and unmaps the
> unwanted parts. Then os::workaround_expand_exec_shield_cs_limit() re-
> mmap()s the wanted part with MAP_FIXED. If this fails at any point it
> is not a fatal error.
>
> So if we change vm_start_gap() to take the stack limit into account
> (when it's finite) that should neutralise
> os::workaround_expand_exec_shield_cs_limit(). I'll try this.
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?
Ben.
Subject: [1/2] mmap: Skip a single VM_NONE mapping when checking the stack gap
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
mm/mmap.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index a5e3dcd75e79..c7906ae1a7a1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2323,11 +2323,16 @@ int expand_downwards(struct vm_area_struct *vma,
if (error)
return error;
- /* Enforce stack_guard_gap */
+ /*
+ * Enforce stack_guard_gap. Some applications allocate a VM_NONE
+ * mapping just below the stack, which we can safely ignore.
+ */
gap_addr = address - stack_guard_gap;
if (gap_addr > address)
return -ENOMEM;
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) {
if (!(prev->vm_flags & VM_GROWSDOWN))
return -ENOMEM;
Subject: [2/2] mmap: Avoid mapping anywhere within the full stack extent
if finite
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/linux/mm.h | 9 ++++-----
mm/mmap.c | 19 +++++++++++++++++++
2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6f543a47fc92..2240a0505072 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2223,15 +2223,14 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
return vma;
}
+unsigned long __vm_start_gap(struct vm_area_struct *vma);
+
static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
{
unsigned long vm_start = vma->vm_start;
- if (vma->vm_flags & VM_GROWSDOWN) {
- vm_start -= stack_guard_gap;
- if (vm_start > vma->vm_start)
- vm_start = 0;
- }
+ if (vma->vm_flags & VM_GROWSDOWN)
+ vm_start = __vm_start_gap(vma);
return vm_start;
}
diff --git a/mm/mmap.c b/mm/mmap.c
index c7906ae1a7a1..f8131a94e56e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2307,6 +2307,25 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
}
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
+unsigned long __vm_start_gap(struct vm_area_struct *vma)
+{
+ unsigned long stack_limit =
+ current->signal->rlim[RLIMIT_STACK].rlim_cur;
+ unsigned long vm_start;
+
+ if (stack_limit != RLIM_INFINITY &&
+ vma->vm_end - vma->vm_start < stack_limit)
+ vm_start = vma->vm_end - PAGE_ALIGN(stack_limit);
+ else
+ vm_start = vma->vm_start;
+
+ vm_start -= stack_guard_gap;
+ if (vm_start > vma->vm_start)
+ vm_start = 0;
+
+ return vm_start;
+}
+
/*
* vma is the first one with address < vma->vm_start. Have to extend vma.
*/
--
Ben Hutchings
For every complex problem
there is a solution that is simple, neat, and wrong.
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
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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