[patch 162/166] kasan: unset panic_on_warn before calling panic()

Andrew Morton
2020-04-07T03:12:45Z

From: Kees Cook <keescook@chromium.org>
Subject: kasan: unset panic_on_warn before calling panic()

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

Link: http://lkml.kernel.org/r/20200227193516.32566-6-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/kasan/report.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/mm/kasan/report.c~kasan-unset-panic_on_warn-before-calling-panic
+++ a/mm/kasan/report.c
@@ -92,8 +92,16 @@ static void end_report(unsigned long *fl
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();
}

_