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Fri, 04 Oct 2019 21:29:50 -0700 (PDT) MIME-Version: 1.0 References: <0000000000009b403005942237bf@google.com> In-Reply-To: <0000000000009b403005942237bf@google.com> From: Dmitry Vyukov Date: Sat, 5 Oct 2019 06:29:39 +0200 Message-ID: Subject: Re: KCSAN: data-race in taskstats_exit / taskstats_exit To: syzbot , Christian Brauner Cc: bsingharora@gmail.com, Marco Elver , LKML , syzkaller-bugs Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 5, 2019 at 6:26 AM syzbot wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: b4bd9343 x86, kcsan: Enable KCSAN for x86 > git tree: https://github.com/google/ktsan.git kcsan > console output: https://syzkaller.appspot.com/x/log.txt?x=125329db600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c0906aa620713d80 > dashboard link: https://syzkaller.appspot.com/bug?extid=c5d03165a1bd1dead0c1 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+c5d03165a1bd1dead0c1@syzkaller.appspotmail.com +Christian, you wanted races in process mgmt ;) > ================================================================== > BUG: KCSAN: data-race in taskstats_exit / taskstats_exit > > write to 0xffff8881157bbe10 of 8 bytes by task 7951 on cpu 0: > taskstats_tgid_alloc kernel/taskstats.c:567 [inline] > taskstats_exit+0x6b7/0x717 kernel/taskstats.c:596 > do_exit+0x2c2/0x18e0 kernel/exit.c:864 > do_group_exit+0xb4/0x1c0 kernel/exit.c:983 > get_signal+0x2a2/0x1320 kernel/signal.c:2734 > do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815 > exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159 > prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] > syscall_return_slowpath arch/x86/entry/common.c:274 [inline] > do_syscall_64+0x2d7/0x2f0 arch/x86/entry/common.c:299 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > read to 0xffff8881157bbe10 of 8 bytes by task 7949 on cpu 1: > taskstats_tgid_alloc kernel/taskstats.c:559 [inline] > taskstats_exit+0xb2/0x717 kernel/taskstats.c:596 > do_exit+0x2c2/0x18e0 kernel/exit.c:864 > do_group_exit+0xb4/0x1c0 kernel/exit.c:983 > __do_sys_exit_group kernel/exit.c:994 [inline] > __se_sys_exit_group kernel/exit.c:992 [inline] > __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:992 > do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 1 PID: 7949 Comm: syz-executor.3 Not tainted 5.3.0+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > ================================================================== > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 7949 Comm: syz-executor.3 Not tainted 5.3.0+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xf5/0x159 lib/dump_stack.c:113 > panic+0x209/0x639 kernel/panic.c:219 > end_report kernel/kcsan/report.c:135 [inline] > kcsan_report.cold+0x57/0xeb kernel/kcsan/report.c:283 > __kcsan_setup_watchpoint+0x342/0x500 kernel/kcsan/core.c:456 > __tsan_read8 kernel/kcsan/kcsan.c:31 [inline] > __tsan_read8+0x2c/0x30 kernel/kcsan/kcsan.c:31 > taskstats_tgid_alloc kernel/taskstats.c:559 [inline] > taskstats_exit+0xb2/0x717 kernel/taskstats.c:596 > do_exit+0x2c2/0x18e0 kernel/exit.c:864 > do_group_exit+0xb4/0x1c0 kernel/exit.c:983 > __do_sys_exit_group kernel/exit.c:994 [inline] > __se_sys_exit_group kernel/exit.c:992 [inline] > __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:992 > do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x459a59 > Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007ffc4ccf3408 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 000000000000001e RCX: 0000000000459a59 > RDX: 0000000000413741 RSI: fffffffffffffff7 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 000000007f8e4506 R09: 00007ffc4ccf3460 > R10: ffffffff81007108 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007ffc4ccf3460 R14: 0000000000000000 R15: 00007ffc4ccf3470 > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/0000000000009b403005942237bf%40google.com.