[PATCH v4 5/6] kasan: Unset panic_on_warn before calling panic()

[Kees Cook]

As done in the full WARN() handler, panic_on_warn needs to be cleared
before calling panic() to avoid recursive panics.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
 mm/kasan/report.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 5ef9f24f566b..54bd98a1fc7b 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -92,8 +92,16 @@ 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) {
+		/*
+		 * This thread may hit another WARN() in the panic path.
+		 * Resetting this prevents additional WARN() from panicking the
+		 * system on this thread.  Other threads are blocked by the
+		 * panic_mutex in panic().
+		 */
+		panic_on_warn = 0;
 		panic("panic_on_warn set ...\n");
+	}
 	kasan_enable_current();
 }
 
-- 
2.20.1