Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752024AbdIFIHg (ORCPT ); Wed, 6 Sep 2017 04:07:36 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:47642 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938AbdIFIHc (ORCPT ); Wed, 6 Sep 2017 04:07:32 -0400 Date: Wed, 6 Sep 2017 10:07:27 +0200 (CEST) From: Thomas Gleixner To: John Stultz cc: Shankara Pailoor , lkml , syzkaller , Stephen Boyd Subject: Re: UBSAN: Undefined error in time.h signed integer overflow In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2059 Lines: 46 On Tue, 5 Sep 2017, John Stultz wrote: > On Tue, Sep 5, 2017 at 9:30 PM, Shankara Pailoor wrote: > > Hi, > > > > I encountered this bug while fuzzing linux kernel 4.13-rc7 with syzkaller. > > > > ================================================================================ > > UBSAN: Undefined behaviour in ./include/linux/time.h:233:27 > > signed integer overflow: > > 8391720337152500783 * 1000000000 cannot be represented in type 'long int' > > CPU: 0 PID: 31798 Comm: syz-executor2 Not tainted 4.13.0-rc7 #2 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > > Ubuntu-1.8.2-1ubuntu1 04/01/2014 > > Call Trace: > > __dump_stack lib/dump_stack.c:16 [inline] > > dump_stack+0xf7/0x1ae lib/dump_stack.c:52 > > ubsan_epilogue+0x12/0x8f lib/ubsan.c:164 > > handle_overflow+0x21e/0x292 lib/ubsan.c:195 > > __ubsan_handle_mul_overflow+0x2a/0x3e lib/ubsan.c:219 > > timespec_to_ns include/linux/time.h:233 [inline] > > posix_cpu_timer_set+0xb5c/0xf20 kernel/time/posix-cpu-timers.c:686 > > do_timer_settime+0x1f4/0x390 kernel/time/posix-timers.c:890 > > SYSC_timer_settime kernel/time/posix-timers.c:916 [inline] > > SyS_timer_settime+0xea/0x170 kernel/time/posix-timers.c:902 > > entry_SYSCALL_64_fastpath+0x18/0xad > > RIP: 0033:0x451e59 > > RSP: 002b:00007fb62af4fc08 EFLAGS: 00000216 ORIG_RAX: 00000000000000df > > RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 0000000000451e59 > > RDX: 0000000020006000 RSI: 0000000000000000 RDI: 0000000000000000 > > RBP: 0000000000000046 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000020003fe0 R11: 0000000000000216 R12: 00000000004be920 > > R13: 00000000ffffffff R14: ffffffffffffffff R15: 0000000000000000 > > ================================================================================ > > Looks similar to the issue Thomas fixed here: > https://patchwork.kernel.org/patch/9799827/ > > > Thomas: Should we change timespec_to_ns() to use the same transition > internally rather then trying to track all the callers? Probably. Thanks, tglx