2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>:
> We we end up calling kasan_report in real mode, our shadow mapping
> for even spinlock variable will show poisoned.
Generally I agree with this patch. We should disable reports when we
print report as early
as possible to prevent recursion in case of bug in spinlock or printk etc.
But I don't understand what is the problem that you observing.
How we ended up with shadow poisoned for a valid spinlock struct?
And since shadow poisoned for some valid memory we should get
enormous amount of false positive reports.
> This will result
> in us calling kasan_report_error with lock_report spin lock held.
> To prevent this disable kasan reporting when we are priting
> error w.r.t kasan.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> ---
> mm/kasan/report.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 79fbc5d14bd2..82b41eb83e43 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -185,6 +185,10 @@ void kasan_report_error(struct kasan_access_info *info)
> {
> unsigned long flags;
>
> + /*
> + * Make sure we don't end up in loop.
> + */
> + kasan_disable_current();
> spin_lock_irqsave(&report_lock, flags);
> pr_err("================================="
> "=================================\n");
> @@ -194,12 +198,17 @@ void kasan_report_error(struct kasan_access_info *info)
> pr_err("================================="
> "=================================\n");
> spin_unlock_irqrestore(&report_lock, flags);
> + kasan_enable_current();
> }
>
> void kasan_report_user_access(struct kasan_access_info *info)
> {
> unsigned long flags;
>
> + /*
> + * Make sure we don't end up in loop.
> + */
> + kasan_disable_current();
> spin_lock_irqsave(&report_lock, flags);
> pr_err("================================="
> "=================================\n");
> @@ -212,6 +221,7 @@ void kasan_report_user_access(struct kasan_access_info
> *info)
> pr_err("================================="
> "=================================\n");
> spin_unlock_irqrestore(&report_lock, flags);
> + kasan_enable_current();
> }
>
> void kasan_report(unsigned long addr, size_t size,
> --
> 2.5.0
>
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
