Re: [PATCH] arm64: increase stack size for KASAN_EXTRA

Arnd Bergmann
2018-12-11T12:42:44Z

On Fri, Dec 7, 2018 at 11:35 PM Qian Cai <cai@lca.pw> wrote:
>
> If the kernel is configured with KASAN_EXTRA, the stack size is
> increasted significantly due to enable this option will set
> -fstack-reuse to "none" in GCC [1]. As the results, it could trigger
> stack overrun quite often with 32k stack size compiled using GCC 8. For
> example, this reproducer

>
> size
> 7536 shrink_inactive_list
> 7440 shrink_page_list
> 6560 fscache_stats_show
> 3920 jbd2_journal_commit_transaction
> 3216 try_to_unmap_one
> 3072 migrate_page_move_mapping
> 3584 migrate_misplaced_transhuge_page
> 3920 ip_vs_lblcr_schedule
> 4304 lpfc_nvme_info_show
> 3888 lpfc_debugfs_nvmestat_data.constprop
>
> There are other 49 functions are over 2k in size while compiling kernel
> with "-Wframe-larger-than=" on this machine. Hence, it is too much work
> to change Makefiles for each object to compile without
> -fsanitize-address-use-after-scope individually.
>
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715#c23

Could you clarify: are the numbers you see with or without the bugfix
from that bugzilla?

Arnd