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From: David Gow <davidgow@google.com>
To: trishalfonso@google.com, brendanhiggins@google.com,
	aryabinin@virtuozzo.com, dvyukov@google.com, mingo@redhat.com,
	peterz@infradead.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, andreyknvl@google.com,
	shuah@kernel.org
Cc: David Gow <davidgow@google.com>,
	linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
	kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org
Subject: [PATCH v10 5/5] mm: kasan: Do not panic if both panic_on_warn and kasan_multishot set
Date: Sat,  1 Aug 2020 00:09:24 -0700
Message-ID: <20200801070924.1786166-6-davidgow@google.com> (raw)
In-Reply-To: <20200801070924.1786166-1-davidgow@google.com>

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
kasan_multishot.

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@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
---
 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)
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	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
-- 
2.28.0.163.g6104cc2f0b6-goog


  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01  7:09 [PATCH v10 0/5] KASAN-KUnit Integration David Gow
2020-08-01  7:09 ` [PATCH v10 1/5] Add KUnit Struct to Current Task David Gow
2020-08-01  7:09 ` [PATCH v10 2/5] KUnit: KASAN Integration David Gow
2020-08-01  7:09 ` [PATCH v10 3/5] KASAN: Port KASAN Tests to KUnit David Gow
2020-08-03 22:58   ` David Gow
2020-08-04 10:15     ` Andrey Konovalov
2020-08-04 23:15       ` David Gow
2020-08-01  7:09 ` [PATCH v10 4/5] KASAN: Testing Documentation David Gow
2020-08-01  7:09 ` David Gow [this message]
2020-08-03 16:25 ` [PATCH v10 0/5] KASAN-KUnit Integration Andrey Konovalov

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