On Tue 28-08-18 08:30:02, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 5b394b2ddf03 Linux 4.19-rc1 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=14f4d8e1400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=49927b422dcf0b29 > dashboard link: https://syzkaller.appspot.com/bug?extid=45a34334c61a8ecf661d > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13127e5a400000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+45a34334c61a8ecf661d@xxxxxxxxxxxxxxxxxxxxxxxxx > > IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready > IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready > IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready > 8021q: adding VLAN 0 to HW filter on device team0 > ================================================================== > BUG: KASAN: stack-out-of-bounds in schedule_debug kernel/sched/core.c:3285 > [inline] > BUG: KASAN: stack-out-of-bounds in __schedule+0x1977/0x1df0 > kernel/sched/core.c:3395 > Read of size 8 at addr ffff8801ad090000 by task syz-executor0/4718 Weird, can you please help me decipher this? So here KASAN complains about wrong memory access in the scheduler. However the stacktrace below shows a problem in find_stack() function called by KASAN? And this does not seem to be fs related at all? Also the reproducer has no sign of any filesystem related activity... Honza > CPU: 0 PID: 4718 Comm: syz-executor0 Not tainted 4.19.0-rc1+ #211 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > > The buggy address belongs to the page: > page:ffffea0006b42400 count:1 mapcount:-512 mapping:0000000000000000 > index:0x0 > flags: 0x2fffc0000000000() > raw: 02fffc0000000000 dead000000000100 dead000000000200 0000000000000000 > raw: 0000000000000000 0000000000000000 00000001fffffdff ffff8801d29544c0 > page dumped because: kasan: bad access detected > page->mem_cgroup:ffff8801d29544c0 > > Memory state around the buggy address: > ffff8801ad08ff00: f2 f2 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 00 00 > ffff8801ad08ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 > > ffff8801ad090000: f1 f1 f1 00 f2 f2 f2 f2 f2 f2 f2 04 f2 f2 f2 f2 > ^ > ffff8801ad090080: f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 00 00 00 00 > ffff8801ad090100: 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 > ================================================================== > Kernel panic - not syncing: panic_on_warn set ... > > BUG: unable to handle kernel paging request at 0000000100000007 > PGD 1b34a2067 P4D 1b34a2067 PUD 0 > Oops: 0000 [#1] SMP KASAN > CPU: 1 PID: 4325 Comm: rs:main Q:Reg Tainted: G B 4.19.0-rc1+ > #211 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:find_stack lib/stackdepot.c:188 [inline] > RIP: 0010:depot_save_stack+0x120/0x470 lib/stackdepot.c:238 > Code: 0f 00 4e 8b 24 f5 e0 db ae 89 4d 85 e4 0f 84 d4 00 00 00 44 8d 47 ff > 49 c1 e0 03 eb 0d 4d 8b 24 24 4d 85 e4 0f 84 bd 00 00 00 <41> 39 5c 24 08 75 > ec 41 3b 7c 24 0c 75 e5 48 8b 01 49 39 44 24 18 > RSP: 0018:ffff8801b2636f40 EFLAGS: 00010006 > RAX: 0000000084727a0d RBX: 00000000222ca320 RCX: ffff8801b2636fa0 > RDX: 000000004e510a9d RSI: 0000000000400000 RDI: 0000000000000012 > RBP: ffff8801b2636f78 R08: 0000000000000088 R09: 00000000dcf06c78 > R10: 00000000ecfd654a R11: ffff8801db1236f3 R12: 00000000ffffffff > R13: ffff8801b2636f88 R14: 00000000000ca320 R15: ffff8801b2a72680 > FS: 00007ff2eb061700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000100000007 CR3: 00000001b4fdd000 CR4: 00000000001406e0 > Call Trace: > save_stack+0xa9/0xd0 mm/kasan/kasan.c:454 > set_track mm/kasan/kasan.c:460 [inline] > __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 > kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 > __cache_free mm/slab.c:3498 [inline] > kmem_cache_free+0x86/0x280 mm/slab.c:3756 > jbd2_free_handle include/linux/jbd2.h:1426 [inline] > jbd2_journal_stop+0x443/0x1600 fs/jbd2/transaction.c:1787 > __ext4_journal_stop+0xde/0x1f0 fs/ext4/ext4_jbd2.c:103 > ext4_dirty_inode+0xab/0xc0 fs/ext4/inode.c:6027 > __mark_inode_dirty+0x760/0x1300 fs/fs-writeback.c:2129 > generic_update_time+0x26a/0x450 fs/inode.c:1651 > update_time fs/inode.c:1667 [inline] > file_update_time+0x390/0x640 fs/inode.c:1877 > __generic_file_write_iter+0x1dc/0x630 mm/filemap.c:3214 > ext4_file_write_iter+0x390/0x1450 fs/ext4/file.c:266 > call_write_iter include/linux/fs.h:1807 [inline] > new_sync_write fs/read_write.c:474 [inline] > __vfs_write+0x6af/0x9d0 fs/read_write.c:487 > vfs_write+0x1fc/0x560 fs/read_write.c:549 > ksys_write+0x101/0x260 fs/read_write.c:598 > __do_sys_write fs/read_write.c:610 [inline] > __se_sys_write fs/read_write.c:607 [inline] > __x64_sys_write+0x73/0xb0 fs/read_write.c:607 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x7ff2ecabf19d > Code: d1 20 00 00 75 10 b8 01 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 > 83 ec 08 e8 be fa ff ff 48 89 04 24 b8 01 00 00 00 0f 05 <48> 8b 3c 24 48 89 > c2 e8 07 fb ff ff 48 89 d0 48 83 c4 08 48 3d 01 > RSP: 002b:00007ff2eb05ff90 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 0000000000000400 RCX: 00007ff2ecabf19d > RDX: 0000000000000400 RSI: 0000000002089a90 RDI: 0000000000000005 > RBP: 0000000002089a90 R08: 00000000020d9e00 R09: 656c6c616b7a7973 > R10: 6c656e72656b2072 R11: 0000000000000293 R12: 0000000000000000 > R13: 00007ff2eb060410 R14: 00000000020d9e00 R15: 0000000002089890 > Modules linked in: > Dumping ftrace buffer: > (ftrace buffer empty) > CR2: 0000000100000007 > ---[ end trace fbf1ba842de6c894 ]--- > RIP: 0010:find_stack lib/stackdepot.c:188 [inline] > RIP: 0010:depot_save_stack+0x120/0x470 lib/stackdepot.c:238 > Code: 0f 00 4e 8b 24 f5 e0 db ae 89 4d 85 e4 0f 84 d4 00 00 00 44 8d 47 ff > 49 c1 e0 03 eb 0d 4d 8b 24 24 4d 85 e4 0f 84 bd 00 00 00 <41> 39 5c 24 08 75 > ec 41 3b 7c 24 0c 75 e5 48 8b 01 49 39 44 24 18 > RSP: 0018:ffff8801b2636f40 EFLAGS: 00010006 > RAX: 0000000084727a0d RBX: 00000000222ca320 RCX: ffff8801b2636fa0 > RDX: 000000004e510a9d RSI: 0000000000400000 RDI: 0000000000000012 > RBP: ffff8801b2636f78 R08: 0000000000000088 R09: 00000000dcf06c78 > R10: 00000000ecfd654a R11: ffff8801db1236f3 R12: 00000000ffffffff > R13: ffff8801b2636f88 R14: 00000000000ca320 R15: ffff8801b2a72680 > FS: 00007ff2eb061700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000100000007 CR3: 00000001b4fdd000 CR4: 00000000001406e0 > Shutting down cpus with NMI > Dumping ftrace buffer: > (ftrace buffer empty) > 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@xxxxxxxxxxxxxxxx. > > 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 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
