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Groups > linux.kernel > #1427960
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support |
| Date | 2016-06-21 19:10 +0200 |
| Message-ID | <rMxlv-eK-7@gated-at.bofh.it> (permalink) |
| References | <rMh73-6ol-3@gated-at.bofh.it> <rMh73-6ol-23@gated-at.bofh.it> <rMqN3-4mp-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Jun 21, 2016 at 12:30 AM, Jann Horn <jannh@google.com> wrote:
> On Tue, Jun 21, 2016 at 1:43 AM, Andy Lutomirski <luto@kernel.org> wrote:
>> If CONFIG_VMAP_STACK is selected, kernel stacks are allocated with
>> vmalloc_node.
> [...]
>> static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
>> int node)
>> {
>> +#ifdef CONFIG_VMAP_STACK
>> + struct thread_info *ti = __vmalloc_node_range(
>> + THREAD_SIZE, THREAD_SIZE, VMALLOC_START, VMALLOC_END,
>> + THREADINFO_GFP | __GFP_HIGHMEM, PAGE_KERNEL,
>> + 0, node, __builtin_return_address(0));
>> +
>
> After spender gave some hints on IRC about the guard pages not working
> reliably, I decided to have a closer look at this. As far as I can
> tell, the idea is that __vmalloc_node_range() automatically adds guard
> pages unless the VM_NO_GUARD flag is specified. However, those guard
> pages are *behind* allocations, not in front of them, while a stack
> guard primarily needs to be in front of the allocation. This wouldn't
> matter if all allocations in the vmalloc area had guard pages behind
> them, but if someone first does some data allocation with VM_NO_GUARD
> and then a stack allocation directly behind that, there won't be a
> guard between the data allocation and the stack allocation.
I'm tempted to explicitly disallow VM_NO_GUARD in the vmalloc range.
It has no in-tree users for non-fixed addresses right now.
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[PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 02/13] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 03/13] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
Re: [PATCH v3 03/13] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() Matt Fleming <matt@codeblueprint.co.uk> - 2016-06-21 12:20 +0200
[PATCH v3 11/13] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 06/13] fork: Add generic vmalloced stack support Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Jann Horn <jannh@google.com> - 2016-06-21 12:10 +0200
Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Andy Lutomirski <luto@amacapital.net> - 2016-06-21 19:10 +0200
Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Kees Cook <keescook@chromium.org> - 2016-06-21 19:20 +0200
Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Andy Lutomirski <luto@amacapital.net> - 2016-06-21 19:40 +0200
Re: [kernel-hardening] Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Rik van Riel <riel@redhat.com> - 2016-06-21 20:50 +0200
Re: [kernel-hardening] Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Andy Lutomirski <luto@amacapital.net> - 2016-06-21 21:50 +0200
Re: [kernel-hardening] Re: [PATCH v3 06/13] fork: Add generic vmalloced stack support Arnd Bergmann <arnd@arndb.de> - 2016-06-21 22:00 +0200
[PATCH v3 04/13] mm: Track NR_KERNEL_STACK in KiB instead of number of stacks Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
Re: [PATCH v3 04/13] mm: Track NR_KERNEL_STACK in KiB instead of number of stacks Michal Hocko <mhocko@kernel.org> - 2016-06-22 10:50 +0200
[PATCH v3 07/13] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 08/13] x86/dumpstack: When OOPSing, rewind the stack before do_exit Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 01/13] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
[PATCH v3 09/13] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp Andy Lutomirski <luto@kernel.org> - 2016-06-21 01:50 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-21 06:10 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-21 18:50 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-21 19:20 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-21 19:40 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Kees Cook <keescook@chromium.org> - 2016-06-21 20:20 +0200
Re: [kernel-hardening] Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Rik van Riel <riel@redhat.com> - 2016-06-21 20:30 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-23 03:30 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-23 08:10 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Oleg Nesterov <oleg@redhat.com> - 2016-06-23 16:40 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Linus Torvalds <torvalds@linux-foundation.org> - 2016-06-23 18:40 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-23 18:50 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Oleg Nesterov <oleg@redhat.com> - 2016-06-23 19:20 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Oleg Nesterov <oleg@redhat.com> - 2016-06-23 19:10 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Arnd Bergmann <arnd@arndb.de> - 2016-06-21 11:40 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Kees Cook <keescook@chromium.org> - 2016-06-21 19:30 +0200
Re: [kernel-hardening] Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-21 20:10 +0200
Re: [kernel-hardening] Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Rik van Riel <riel@redhat.com> - 2016-06-21 20:10 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski <luto@amacapital.net> - 2016-06-21 21:50 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Kees Cook <keescook@chromium.org> - 2016-06-21 22:20 +0200
Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core) Arnd Bergmann <arnd@arndb.de> - 2016-06-21 21:50 +0200
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