From: Kees Cook <keescook@xxxxxxxxxxxx> Subject: ubsan: check panic_on_warn Syzkaller expects kernel warnings to panic when the panic_on_warn sysctl is set. More work is needed here to have UBSan reuse the WARN infrastructure, but for now, just check the flag manually. Link: https://lore.kernel.org/lkml/CACT4Y+bsLJ-wFx_TaXqax3JByUOWB3uk787LsyMVcfW6JzzGvg@xxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20200227193516.32566-5-keescook@xxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Elena Petrova <lenaptr@xxxxxxxxxx> Cc: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/ubsan.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/lib/ubsan.c~ubsan-check-panic_on_warn +++ a/lib/ubsan.c @@ -156,6 +156,17 @@ static void ubsan_epilogue(void) "========================================\n"); current->in_ubsan--; + + 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"); + } } static void handle_overflow(struct overflow_data *data, void *lhs, _
