From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Andy Lutomirski <luto@amacapital.net>, Jann Horn <jannh@google.com>
Cc: X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-doc@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Balbir Singh <bsingharora@gmail.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H. J. Lu" <hjl.tools@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
"Shanbhogue, Vedvyas" <vedvyas.shanbhogue@intel.com>,
Daniel Micay <danielmicay@gmail.com>
Subject: Re: [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs
Date: Fri, 12 Oct 2018 14:49:28 -0700 [thread overview]
Message-ID: <1d293d2fb0df99fdb0048825b4e39640840bfabb.camel@intel.com> (raw)
In-Reply-To: <CALCETrUJ1t_K=FQExa_K0yg+aXkPot6wn6RHBPDc3BsAxtmMBw@mail.gmail.com>
On Thu, 2018-10-11 at 13:55 -0700, Andy Lutomirski wrote:
> On Thu, Oct 11, 2018 at 1:39 PM Jann Horn <jannh@google.com> wrote:
> >
> > On Thu, Oct 11, 2018 at 5:20 PM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote:
> > > Create a guard area between VMAs to detect memory corruption.
> >
> > [...]
> > > +config VM_AREA_GUARD
> > > + bool "VM area guard"
> > > + default n
> > > + help
> > > + Create a guard area between VM areas so that access beyond
> > > + limit can be detected.
> > > +
> > > endmenu
> >
> > Sorry to bring this up so late, but Daniel Micay pointed out to me
> > that, given that VMA guards will raise the number of VMAs by
> > inhibiting vma_merge(), people are more likely to run into
> > /proc/sys/vm/max_map_count (which limits the number of VMAs to ~65k by
> > default, and can't easily be raised without risking an overflow of
> > page->_mapcount on systems with over ~800GiB of RAM, see
> > https://lore.kernel.org/lkml/20180208021112.GB14918@bombadil.infradead.org/
> > and replies) with this change.
> >
> > Playing with glibc's memory allocator, it looks like glibc will use
> > mmap() for 128KB allocations; so at 65530*128KB=8GB of memory usage in
> > 128KB chunks, an application could run out of VMAs.
>
> Ugh.
>
> Do we have a free VM flag so we could do VM_GUARD to force a guard
> page? (And to make sure that, when a new VMA is allocated, it won't
> be directly adjacent to a VM_GUARD VMA.)
Maybe something like the following? These vm_start_gap()/vm_end_gap() are used
in many architectures. Do we want to put them in a different series? Comments?
Yu-cheng
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0416a7204be3..92b580542411 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -224,11 +224,13 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit
architectures */
#define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit
architectures */
#define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit
architectures */
+#define VM_HIGH_ARCH_BIT_5 37 /* bit only usable on 64-bit
architectures */
#define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0)
#define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1)
#define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2)
#define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3)
#define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4)
+#define VM_HIGH_ARCH_5 BIT(VM_HIGH_ARCH_BIT_5)
#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
#ifdef CONFIG_ARCH_HAS_PKEYS
@@ -266,6 +268,12 @@ extern unsigned int kobjsize(const void *objp);
# define VM_MPX VM_NONE
#endif
+#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
+#define VM_GUARD VM_HIGH_ARCH_5
+#else
+#define VM_GUARD VM_NONE
+#endif
+
#ifndef VM_GROWSUP
# define VM_GROWSUP VM_NONE
#endif
@@ -2417,24 +2425,34 @@ static inline struct vm_area_struct *
find_vma_intersection(struct mm_struct * m
-static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
+static inline unsigned long vm_start_gap(struct vm_area_struct *vma, vm_flags_t
flags)
{
unsigned long vm_start = vma->vm_start;
+ unsigned long gap = 0;
+
+ if (vma->vm_flags & VM_GROWSDOWN)
+ gap = stack_guard_gap;
+ else if ((vma->vm_flags & VM_GUARD) || (flags & VM_GUARD))
+ gap = PAGE_SIZE;
+
+ vm_start -= gap;
+ if (vm_start > vma->vm_start)
+ vm_start = 0;
- if (vma->vm_flags & VM_GROWSDOWN) {
- vm_start -= stack_guard_gap;
- if (vm_start > vma->vm_start)
- vm_start = 0;
- }
return vm_start;
}
-static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
+static inline unsigned long vm_end_gap(struct vm_area_struct *vma, vm_flags_t
flags)
{
unsigned long vm_end = vma->vm_end;
+ unsigned long gap = 0;
+
+ if (vma->vm_flags & VM_GROWSUP)
+ gap = stack_guard_gap;
+ else if ((vma->vm_flags & VM_GUARD) || (flags & VM_GUARD))
+ gap = PAGE_SIZE;
+
+ vm_end += gap;
+ if (vm_end < vma->vm_end)
+ vm_end = -PAGE_SIZE;
- if (vma->vm_flags & VM_GROWSUP) {
- vm_end += stack_guard_gap;
- if (vm_end < vma->vm_end)
- vm_end = -PAGE_SIZE;
- }
return vm_end;
}
next prev parent reply other threads:[~2018-10-12 21:54 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 15:14 [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 01/27] x86/cpufeatures: Add CPUIDs for Control Flow Enforcement Technology (CET) Yu-cheng Yu
2018-10-11 16:43 ` Borislav Petkov
2018-10-11 16:45 ` Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 02/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2018-10-15 17:03 ` Borislav Petkov
2018-10-11 15:14 ` [PATCH v5 03/27] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2018-10-17 10:41 ` Borislav Petkov
2018-10-17 22:39 ` Randy Dunlap
2018-10-17 22:58 ` Borislav Petkov
2018-10-17 23:17 ` Randy Dunlap
2018-10-18 9:26 ` Borislav Petkov
2018-10-18 9:31 ` Pavel Machek
2018-10-18 12:10 ` Borislav Petkov
2018-10-18 18:33 ` Randy Dunlap
2018-10-18 9:24 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-11-08 18:40 ` Borislav Petkov
2018-11-08 20:40 ` Yu-cheng Yu
2018-11-08 23:52 ` Borislav Petkov
2018-11-11 11:31 ` Pavel Machek
2018-11-11 11:31 ` Pavel Machek
2018-11-11 14:59 ` Andy Lutomirski
2018-11-11 19:02 ` Pavel Machek
2018-11-08 20:46 ` Andy Lutomirski
2018-11-08 21:01 ` Yu-cheng Yu
2018-11-08 21:22 ` Andy Lutomirski
2018-11-08 21:31 ` Cyrill Gorcunov
2018-11-08 22:01 ` Andy Lutomirski
2018-11-08 22:18 ` Cyrill Gorcunov
2018-11-08 21:48 ` Dave Hansen
2018-11-08 22:00 ` Matthew Wilcox
2018-11-08 23:35 ` Dave Hansen
2018-11-09 0:32 ` Matthew Wilcox
2018-11-09 0:45 ` Andy Lutomirski
2018-11-09 17:13 ` Dave Hansen
2018-11-09 17:17 ` Matthew Wilcox
2018-11-09 17:20 ` Dave Hansen
2018-11-09 17:28 ` Dave Hansen
2018-11-11 11:31 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 05/27] Documentation/x86: Add CET description Yu-cheng Yu
2018-11-13 18:43 ` Borislav Petkov
2018-11-13 21:02 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 06/27] x86/cet: Control protection exception handler Yu-cheng Yu
2018-11-14 18:44 ` Borislav Petkov
2018-11-14 20:19 ` Yu-cheng Yu
2018-11-14 20:28 ` Borislav Petkov
2018-10-11 15:15 ` [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs Yu-cheng Yu
2018-10-11 20:39 ` Jann Horn
2018-10-11 20:49 ` Yu-cheng Yu
2018-10-11 20:55 ` Andy Lutomirski
2018-10-12 21:49 ` Yu-cheng Yu [this message]
2018-10-12 13:17 ` Matthew Wilcox
2018-10-11 20:49 ` Dave Hansen
2018-10-12 10:24 ` Florian Weimer
2018-10-11 15:15 ` [PATCH v5 08/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 09/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 10/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 11/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 12/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 13/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 14/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 15/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 16/27] mm: Handle shadow stack page fault Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 17/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 18/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 19/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 20/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 21/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-11-06 18:43 ` Dave Hansen
2018-11-06 18:55 ` Andy Lutomirski
2018-11-06 20:21 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 22/27] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 24/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 25/27] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-10-11 19:21 ` [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Dave Hansen
2018-10-11 19:29 ` Yu-cheng Yu
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