The patch titled
Subject: mm/kasan: prevent deadlock in kasan reporting
has been added to the -mm tree. Its filename is
mm-kasan-prevent-deadlock-in-kasan-reporting.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kasan-prevent-deadlock-in-kasan-reporting.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kasan-prevent-deadlock-in-kasan-reporting.patch
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------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Subject: mm/kasan: prevent deadlock in kasan reporting
When we end up calling kasan_report in real mode, our shadow mapping for
the 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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/report.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff -puN mm/kasan/report.c~mm-kasan-prevent-deadlock-in-kasan-reporting mm/kasan/report.c
--- a/mm/kasan/report.c~mm-kasan-prevent-deadlock-in-kasan-reporting
+++ a/mm/kasan/report.c
@@ -173,12 +173,10 @@ static void print_shadow_for_address(con
* function, because generic functions may try to
* access kasan mapping for the passed address.
*/
- kasan_disable_current();
memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
print_hex_dump(KERN_ERR, buffer,
DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
shadow_buf, SHADOW_BYTES_PER_ROW, 0);
- kasan_enable_current();
if (row_is_guilty(shadow_row, shadow))
pr_err("%*c\n",
@@ -195,6 +193,10 @@ void kasan_report_error(struct kasan_acc
{
unsigned long flags;
+ /*
+ * Make sure we don't end up in loop.
+ */
+ kasan_disable_current();
spin_lock_irqsave(&report_lock, flags);
pr_err("================================="
"=================================\n");
@@ -204,12 +206,17 @@ void kasan_report_error(struct kasan_acc
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");
@@ -222,6 +229,7 @@ void kasan_report_user_access(struct kas
pr_err("================================="
"=================================\n");
spin_unlock_irqrestore(&report_lock, flags);
+ kasan_enable_current();
}
void kasan_report(unsigned long addr, size_t size,
_
Patches currently in -mm which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
mm-kasan-rename-kasan_enabled-to-kasan_report_enabled.patch
mm-kasan-module_vaddr-is-not-available-on-all-archs.patch
mm-kasan-dont-use-kasan-shadow-pointer-in-generic-functions.patch
mm-kasan-prevent-deadlock-in-kasan-reporting.patch
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