Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1213664 > unrolled thread
| Started by | "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> |
|---|---|
| First post | 2015-08-26 10:30 +0200 |
| Last post | 2015-08-30 15:00 +0200 |
| Articles | 3 — 2 participants |
Back to article view | Back to linux.kernel
This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by
below is the oldest one visible, not the original post.
[PATCH V2 09/10] kasan: Prevent deadlock in kasan reporting "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2015-08-26 10:30 +0200
Re: [PATCH V2 09/10] kasan: Prevent deadlock in kasan reporting Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-08-27 14:10 +0200
Re: [PATCH V2 09/10] kasan: Prevent deadlock in kasan reporting "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2015-08-30 15:00 +0200
| From | "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-08-26 10:30 +0200 |
| Subject | [PATCH V2 09/10] kasan: Prevent deadlock in kasan reporting |
| Message-ID | <q1EfN-gF-31@gated-at.bofh.it> |
We we end up calling kasan_report in real mode, our shadow mapping
for even spinlock variable will show poisoned. 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.kumar@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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[toc] | [next] | [standalone]
| From | Andrey Ryabinin <ryabinin.a.a@gmail.com> |
|---|---|
| Date | 2015-08-27 14:10 +0200 |
| Message-ID | <q24ae-3Zi-15@gated-at.bofh.it> |
| In reply to | #1213664 |
2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V <aneesh.kumar@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.kumar@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
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[toc] | [prev] | [next] | [standalone]
| From | "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-08-30 15:00 +0200 |
| Message-ID | <q3ang-11w-11@gated-at.bofh.it> |
| In reply to | #1214494 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> writes: > 2015-08-26 11:26 GMT+03:00 Aneesh Kumar K.V <aneesh.kumar@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. > I still haven't fully isolated all the .c files which should not be kasan instrumented. That means in case of ppc64 i ended up calling kasan _load/_store in real mode. That will result in failure w.r.t to the above spin_lock code. -aneesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[toc] | [prev] | [standalone]
Back to top | Article view | linux.kernel
csiph-web