Re: [lkp] [kallsyms] bf2d2b07db: kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] general protection fault: 0000 [#1] PREEMPT PREEMPT KASANKASAN

From: Guenter Roeck
Date: Mon Feb 01 2016 - 22:49:16 EST


On 02/01/2016 04:20 PM, Andrew Morton wrote:
On Thu, 28 Jan 2016 09:12:15 +0800 kernel test robot <ying.huang@xxxxxxxxxxxxxxx> wrote:

FYI, we noticed the below changes on

https://git.linaro.org/people/ard.biesheuvel/linux-arm arm64-kaslr-v4a
commit bf2d2b07db19001ae0bd55826025b0ba47fae0c2 ("kallsyms: add support for relative offsets in kallsyms address table")


+-----------------------------------------------------------+------------+------------+
| | 2c4d21df0f | bf2d2b07db |
+-----------------------------------------------------------+------------+------------+
| boot_successes | 10 | 0 |
| boot_failures | 6 | 36 |
| Kernel_panic-not_syncing:Attempted_to_kill_init!exitcode= | 2 | |
| IP-Config:Auto-configuration_of_network_failed | 4 | |
| general_protection_fault:#[##]PREEMPT_PREEMPT_KASANKASAN | 0 | 36 |
| general_protection_fault:#[##] | 0 | 36 |
| BUG:kernel_boot_hang | 0 | 36 |
+-----------------------------------------------------------+------------+------------+



[ 0.281636] kasan: CONFIG_KASAN_INLINE enabled

[ 0.282416] kasan: GPF could be caused by NULL-ptr deref or user memory access
[ 0.282416] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] general protection fault: 0000 [#1] PREEMPT PREEMPT KASANKASAN

[ 0.284561] Modules linked in:
[ 0.284561] Modules linked in:

[ 0.285136] CPU: 0 PID: 1 Comm: swapper Not tainted 4.5.0-rc1-00036-gbf2d2b0 #1
[ 0.285136] CPU: 0 PID: 1 Comm: swapper Not tainted 4.5.0-rc1-00036-gbf2d2b0 #1
[ 0.286438] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[ 0.286438] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[ 0.288000] task: ffff88000fcb0000 ti: ffff88000fcb8000 task.ti: ffff88000fcb8000
[ 0.288000] task: ffff88000fcb0000 ti: ffff88000fcb8000 task.ti: ffff88000fcb8000
[ 0.289287] RIP: 0010:[<ffffffff8120688c>]

I'm not sufficiently familiar with KASAN to be able to interpret this.
Perhaps Andrey can shed some light?

The lack of symbol decoding is a problem.

CONFIG_KALLSYMS=y
CONFIG_KALLSYMS_ALL=y
CONFIG_KALLSYMS_BASE_RELATIVE=y

It should be there. Perhaps it is not because this error is itself
(possibly) related to kallsyms changes?


Probably. I had seen something similar (crash and no symbols) with an earlier version of the patch,
if the symbols were not created. There might be a message in the log, indicating that kallsyms
failed to generate the symbols.

Guenter