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.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.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>
Link: http://lkml.kernel.org/r/20200227193516.32566-6-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index cf5c17d..80f23c9 100644 (file)
--- 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();
 }