[PATCH] panic: call panic handlers before kmsg_dump

[PATCH] panic: call panic handlers before kmsg_dump

[Kees Cook]

Since the panic handlers may produce additional information (via printk)
for the kernel log, it should be reported as part of the panic output
saved by kmsg_dump(). Without this re-ordering, nothing that adds
information to a panic will show up in pstore's view when kmsg_dump
runs, and is therefore not visible to crash reporting tools that examine
pstore output.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 kernel/panic.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 8018646..b6c482c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -123,10 +123,14 @@ void panic(const char *fmt, ...)
 	 */
 	smp_send_stop();
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
+	/*
+	 * Run any panic handlers, including those that might need to
+	 * add information to the kmsg dump output.
+	 */
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
+	kmsg_dump(KMSG_DUMP_PANIC);
+
 	bust_spinlocks(0);
 
 	if (!panic_blink)
-- 
1.7.9.5


-- 
Kees Cook
Chrome OS Security

Re: [PATCH] panic: call panic handlers before kmsg_dump

[Tony Luck]

On Thu, Jul 18, 2013 at 4:03 PM, Kees Cook <keescook@chromium.org> wrote:
> Since the panic handlers may produce additional information (via printk)
> for the kernel log, it should be reported as part of the panic output
> saved by kmsg_dump(). Without this re-ordering, nothing that adds
> information to a panic will show up in pstore's view when kmsg_dump
> runs, and is therefore not visible to crash reporting tools that examine
> pstore output.

Good point.

Acked-by: Tony Luck <tony.luck@intel.com>

Re: [PATCH] panic: call panic handlers before kmsg_dump

[Kees Cook]

On Thu, Jul 18, 2013 at 4:17 PM, Tony Luck <tony.luck@gmail.com> wrote:
> On Thu, Jul 18, 2013 at 4:03 PM, Kees Cook <keescook@chromium.org> wrote:
>> Since the panic handlers may produce additional information (via printk)
>> for the kernel log, it should be reported as part of the panic output
>> saved by kmsg_dump(). Without this re-ordering, nothing that adds
>> information to a panic will show up in pstore's view when kmsg_dump
>> runs, and is therefore not visible to crash reporting tools that examine
>> pstore output.
>
> Good point.
>
> Acked-by: Tony Luck <tony.luck@intel.com>

Can someone pick this patch up? If akpm doesn't want it, it could live
in the pstore tree maybe?

-Kees

-- 
Kees Cook
Chrome OS Security

Re: [PATCH] panic: call panic handlers before kmsg_dump

[Kees Cook]

On Tue, Sep 10, 2013 at 3:41 PM, Kees Cook <keescook@chromium.org> wrote:
> On Thu, Jul 18, 2013 at 4:17 PM, Tony Luck <tony.luck@gmail.com> wrote:
>> On Thu, Jul 18, 2013 at 4:03 PM, Kees Cook <keescook@chromium.org> wrote:
>>> Since the panic handlers may produce additional information (via printk)
>>> for the kernel log, it should be reported as part of the panic output
>>> saved by kmsg_dump(). Without this re-ordering, nothing that adds
>>> information to a panic will show up in pstore's view when kmsg_dump
>>> runs, and is therefore not visible to crash reporting tools that examine
>>> pstore output.
>>
>> Good point.
>>
>> Acked-by: Tony Luck <tony.luck@intel.com>
>
> Can someone pick this patch up? If akpm doesn't want it, it could live
> in the pstore tree maybe?

Ah, sorry, it seems like it is already in -mm. Never mind!

-Kees

-- 
Kees Cook
Chrome OS Security