Messages in this thread | | | From | Dmitry Vyukov <> | Date | Sat, 8 Dec 2018 12:02:02 +0100 | Subject | Re: general protection fault in freeary |
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On Sat, Dec 8, 2018 at 11:51 AM syzbot <syzbot+9d8b6fa6ee7636f350c1@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 74c4a24df7ca Add linux-next specific files for 20181207 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=11a713d5400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6e9413388bf37bed > dashboard link: https://syzkaller.appspot.com/bug?extid=9d8b6fa6ee7636f350c1 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16e19da3400000
Hi Manfred,
This looks very similar to the one we discussed recently: BUG: corrupted list in freeary https://syzkaller.appspot.com/bug?id=86ea6558f833e79c46e1e3adb33630d6078ac80a https://groups.google.com/forum/#!msg/syzkaller-bugs/MquajglkT3U/LG9O7zhFCAAJ
So this may be the "more info" that we were waiting for.
Looking at the repro:
#{"threaded":true,"collide":true,"repeat":true,"procs":6} unshare(0x8020000) semget$private(0x0, 0x4007, 0x0)
It looks a super subtle race that does not require anything special beyond unshare+semget.
> IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+9d8b6fa6ee7636f350c1@syzkaller.appspotmail.com > > dmaengine-unmap-16 0KB 4KB > dmaengine-unmap-2 0KB 3KB > kasan: CONFIG_KASAN_INLINE enabled > skbuff_fclone_cache 5KB 7KB > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 21755 Comm: syz-executor0 Not tainted 4.20.0-rc5-next-20181207+ > #163 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:__list_del_entry_valid+0x84/0x100 lib/list_debug.c:51 > Code: 0f 84 60 01 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 39 01 > 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 > 5f 49 8b 14 24 48 39 da 0f 85 4e 01 00 00 49 8d 7d > RSP: 0018:ffff8881b5ea6ec0 EFLAGS: 00010a06 > RAX: dffffc0000000000 RBX: ffffffff87dd7df8 RCX: ffffffff8341d7fe > RDX: 11699ffffec411b1 RSI: ffffffff8341d556 RDI: ffffffff87dd7e00 > skbuff_head_cache 539KB 1706KB > RBP: ffff8881b5ea6ed8 R08: ffff8881baf76300 R09: fffff5200198e400 > R10: fffff5200198e400 R11: ffffc9000cc72003 R12: 8b4cfffff6208d8b > R13: 48fffff618b58b48 R14: ffff8881b5ea72c0 R15: dffffc0000000000 > FS: 000000000279f940(0000) GS:ffff8881dad00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000000072c000 CR3: 00000001c031f000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __list_del_entry include/linux/list.h:117 [inline] > list_del include/linux/list.h:125 [inline] > unlink_queue ipc/sem.c:786 [inline] > freeary+0xe72/0x1a40 ipc/sem.c:1164 > configfs_dir_cache 0KB 4KB > file_lock_cache 0KB 3KB > file_lock_ctx 0KB 3KB > fsnotify_mark_connector 43KB 55KB > free_ipcs+0x9f/0x1c0 ipc/namespace.c:112 > sem_exit_ns+0x20/0x40 ipc/sem.c:237 > free_ipc_ns ipc/namespace.c:120 [inline] > put_ipc_ns+0x66/0x180 ipc/namespace.c:152 > net_namespace 52KB 52KB > free_nsproxy+0xcf/0x220 kernel/nsproxy.c:180 > switch_task_namespaces+0xb3/0xd0 kernel/nsproxy.c:229 > exit_task_namespaces+0x17/0x20 kernel/nsproxy.c:234 > do_exit+0x1a48/0x2620 kernel/exit.c:866 > shmem_inode_cache 5754KB 6042KB > task_delay_info 112KB 484KB > taskstats 152KB 163KB > proc_dir_entry 578KB 581KB > do_group_exit+0x177/0x440 kernel/exit.c:970 > get_signal+0x8b0/0x1980 kernel/signal.c:2515 > pde_opener 0KB 3KB > do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 > seq_file 282KB 342KB > sigqueue 39KB 208KB > kernfs_node_cache 11484KB 11489KB > mnt_cache 5951KB 6436KB > exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 > prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] > syscall_return_slowpath arch/x86/entry/common.c:268 [inline] > do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 > filp 3938KB 6761KB > entry_SYSCALL_64_after_hwframe+0x49/0xbe > names_cache 99560KB 99598KB > RIP: 0033:0x459f39 > Code: ff 48 85 f6 0f 84 27 8a fb ff 48 83 ee 10 48 89 4e 08 48 89 3e 48 89 > d7 4c 89 c2 4d 89 c8 4c 8b 54 24 08 b8 38 00 00 00 0f 05 <48> 85 c0 0f 8c > fe 89 fb ff 74 01 c3 31 ed 48 f7 c7 00 00 01 00 75 > RSP: 002b:00007ffd923f9ef8 EFLAGS: 00000202 ORIG_RAX: 0000000000000038 > RAX: fffffffffffffff4 RBX: 00007f99b9efc700 RCX: 0000000000459f39 > RDX: 00007f99b9efc9d0 RSI: 00007f99b9efbdb0 RDI: 00000000003d0f00 > iint_cache 87KB 91KB > RBP: 00007ffd923fa100 R08: 00007f99b9efc700 R09: 00007f99b9efc700 > R10: 00007f99b9efc9d0 R11: 0000000000000202 R12: 0000000000000000 > R13: 00007ffd923f9faf R14: 00007f99b9efc9c0 R15: 0000000000000001 > Modules linked in: > ---[ end trace 984887003f1a69a9 ]--- > RIP: 0010:__list_del_entry_valid+0x84/0x100 lib/list_debug.c:51 > key_jar 3KB 7KB > Code: 0f 84 60 01 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 39 01 > 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 > 5f 49 8b 14 24 48 39 da 0f 85 4e 01 00 00 49 8d 7d > RSP: 0018:ffff8881b5ea6ec0 EFLAGS: 00010a06 > RAX: dffffc0000000000 RBX: ffffffff87dd7df8 RCX: ffffffff8341d7fe > RDX: 11699ffffec411b1 RSI: ffffffff8341d556 RDI: ffffffff87dd7e00 > RBP: ffff8881b5ea6ed8 R08: ffff8881baf76300 R09: fffff5200198e400 > uts_namespace 2KB 7KB > R10: fffff5200198e400 R11: ffffc9000cc72003 R12: 8b4cfffff6208d8b > R13: 48fffff618b58b48 R14: ffff8881b5ea72c0 R15: dffffc0000000000 > FS: 000000000279f940(0000) GS:ffff8881dad00000(0000) knlGS:0000000000000000 > nsproxy 63KB 75KB > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000000072c000 CR3: 00000001c031f000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > 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#bug-status-tracking for how to communicate with > syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > > -- > 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/0000000000000e2b4e057c80822f%40google.com. > For more options, visit https://groups.google.com/d/optout.
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