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Subject[PATCH V2 09/10] kasan: Prevent deadlock in kasan reporting
Date
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


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