[PATCH v13 5/5] mm: kasan: Do not panic if both panic_on_warn and kasan_multishot set

From: David Gow
Date: Thu Sep 10 2020 - 03:06:35 EST

KASAN errors will currently trigger a panic when panic_on_warn is set.
This renders kasan_multishot useless, as further KASAN errors won't be
reported if the kernel has already paniced. By making kasan_multishot
disable this behaviour for KASAN errors, we can still have the benefits
of panic_on_warn for non-KASAN warnings, yet be able to use

This is particularly important when running KASAN tests, which need to
trigger multiple KASAN errors: previously these would panic the system
if panic_on_warn was set, now they can run (and will panic the system
should non-KASAN warnings show up).

Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
mm/kasan/report.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index e2c14b10bc81..00a53f1355ae 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -95,7 +95,7 @@ static void end_report(unsigned long *flags)
spin_unlock_irqrestore(&report_lock, *flags);
- if (panic_on_warn) {
+ if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
* This thread may hit another WARN() in the panic path.
* Resetting this prevents additional WARN() from panicking the