From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
x86@kernel.org, Borislav Petkov <bp@alien8.de>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Brian Gerst <brgerst@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [kernel-hardening] Re: [PATCH 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow
Date: Thu, 16 Jun 2016 13:16:42 -0500 [thread overview]
Message-ID: <20160616181642.r2bpceuvvffttp7r@treble> (raw)
In-Reply-To: <f3202c855a2a61ae4c37d8b3835e00fb384c56b9.1466036668.git.luto@kernel.org>
On Wed, Jun 15, 2016 at 05:28:32PM -0700, Andy Lutomirski wrote:
> If we overflow the stack, print_context_stack will abort. Detect
> this case and rewind back into the valid part of the stack so that
> we can trace it.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> arch/x86/kernel/dumpstack.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
> index d4d085e27d04..400a2e17c1d1 100644
> --- a/arch/x86/kernel/dumpstack.c
> +++ b/arch/x86/kernel/dumpstack.c
> @@ -100,6 +100,13 @@ print_context_stack(struct thread_info *tinfo,
> {
> struct stack_frame *frame = (struct stack_frame *)bp;
>
> + /*
> + * If we overflowed the stack into a guard page, jump back to the
> + * bottom of the usable stack.
> + */
> + if ((unsigned long)tinfo - (unsigned long)stack < PAGE_SIZE)
> + stack = (unsigned long *)tinfo + 1;
That will start walking the stack in the middle of the thread_info
struct.
I think you meant:
stack = (unsigned long *)(tinfo + 1)
However, thread_info will have been overwritten anyway. So maybe it
should just be:
stack = tinfo;
(Though that still wouldn't quite work because the valid_stack_ptr()
check would fail...)
> +
> while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) {
> unsigned long addr;
--
Josh
next prev parent reply other threads:[~2016-06-16 18:16 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 0:28 [kernel-hardening] [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 01/13] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 02/13] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 03/13] x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of number of stacks Andy Lutomirski
2016-06-16 11:10 ` [kernel-hardening] " Vladimir Davydov
2016-06-16 17:21 ` Andy Lutomirski
2016-06-16 19:20 ` Andy Lutomirski
2016-06-16 15:33 ` Josh Poimboeuf
2016-06-16 17:39 ` Andy Lutomirski
2016-06-16 19:39 ` Josh Poimboeuf
2016-06-16 0:28 ` [kernel-hardening] [PATCH 05/13] mm: Move memcg stack accounting to account_kernel_stack Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 06/13] fork: Add generic vmalloced stack support Andy Lutomirski
2016-06-16 17:25 ` [kernel-hardening] " Kees Cook
2016-06-16 17:37 ` Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 07/13] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 08/13] x86/dumpstack: When OOPSing, rewind the stack before do_exit Andy Lutomirski
2016-06-16 17:50 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 17:57 ` Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 09/13] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp Andy Lutomirski
2016-06-16 11:56 ` [kernel-hardening] " Borislav Petkov
2016-06-16 0:28 ` [kernel-hardening] [PATCH 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski
2016-06-16 18:16 ` Josh Poimboeuf [this message]
2016-06-16 18:22 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 18:33 ` Josh Poimboeuf
2016-06-16 18:37 ` Andy Lutomirski
2016-06-16 18:54 ` Josh Poimboeuf
2016-06-16 0:28 ` [kernel-hardening] [PATCH 11/13] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] [PATCH 12/13] x86/mm/64: Enable vmapped stacks Andy Lutomirski
2016-06-16 4:17 ` [kernel-hardening] " Mika Penttilä
2016-06-16 5:33 ` Andy Lutomirski
2016-06-16 13:11 ` Rik van Riel
2016-06-16 0:28 ` [kernel-hardening] [PATCH 13/13] x86/mm: Improve stack-overflow #PF handling Andy Lutomirski
2016-06-16 6:05 ` [kernel-hardening] Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) Heiko Carstens
2016-06-16 17:50 ` Andy Lutomirski
2016-06-16 18:14 ` Andy Lutomirski
2016-06-16 21:27 ` Andy Lutomirski
2016-06-17 3:58 ` Andy Lutomirski
2016-06-17 7:27 ` Heiko Carstens
2016-06-17 17:38 ` Andy Lutomirski
2016-06-20 5:58 ` Heiko Carstens
2016-06-20 6:01 ` Andy Lutomirski
2016-06-20 7:07 ` Heiko Carstens
2016-06-16 17:24 ` Kees Cook
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