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From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Elena Petrova <lenaptr@google.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Alexander Potapenko <glider@google.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	kasan-dev@googlegroups.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	kernel-hardening@lists.openwall.com, syzkaller@googlegroups.com
Subject: [PATCH v5 4/6] ubsan: Check panic_on_warn
Date: Thu, 27 Feb 2020 11:35:14 -0800
Message-ID: <20200227193516.32566-5-keescook@chromium.org> (raw)
In-Reply-To: <20200227193516.32566-1-keescook@chromium.org>

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@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 lib/ubsan.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/ubsan.c b/lib/ubsan.c
index 7b9b58aee72c..429663eef6a7 100644
--- a/lib/ubsan.c
+++ b/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,
-- 
2.20.1


  parent reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-27 19:35 [PATCH v5 0/6] ubsan: Split out bounds checker Kees Cook
2020-02-27 19:35 ` [PATCH v5 1/6] ubsan: Add trap instrumentation option Kees Cook
2020-02-27 19:35 ` [PATCH v5 2/6] ubsan: Split "bounds" checker from other options Kees Cook
2020-02-27 19:35 ` [PATCH v5 3/6] lkdtm/bugs: Add arithmetic overflow and array bounds checks Kees Cook
2020-02-27 19:35 ` Kees Cook [this message]
2020-02-27 19:35 ` [PATCH v5 5/6] kasan: Unset panic_on_warn before calling panic() Kees Cook
2020-02-27 19:35 ` [PATCH v5 6/6] ubsan: Include bug type in report header Kees Cook
2020-02-28 12:45   ` Andrey Konovalov

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