On Tue, Sep 15, 2020 at 01:04:20AM -0700, syzbot wrote: > syzbot found the following issue on: > > HEAD commit: 581cb3a2 Merge tag 'f2fs-for-5.9-rc5' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11f5c011900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9 > dashboard link: https://syzkaller.appspot.com/bug?extid=1594adb1b44e354153d8 > compiler: gcc (GCC) 10.1.0-syz 20200507 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+1594adb1b44e354153d8@xxxxxxxxxxxxxxxxxxxxxxxxx > > general protection fault, probably for non-canonical address 0xdffffc0012e34a9a: 0000 [#1] PREEMPT SMP KASAN > KASAN: probably user-memory-access in range [0x00000000971a54d0-0x00000000971a54d7] > CPU: 1 PID: 19990 Comm: kworker/1:11 Not tainted 5.9.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: events_power_efficient do_cache_clean > RIP: 0010:cache_clean+0x119/0x7f0 net/sunrpc/cache.c:444 That's in cache_clean(): spin_lock(&cache_list_lock); ... current_detail = list_entry(next, struct cache_detail, others) 444: if (current_detail->nextcheck > seconds_since_boot()) It suggests cache_list or current_detail (both globals) are corrupted somehow. Those are manipulated only by cache_clean() and sunrpc_{init,destroy}_cache_detail(), always under the cache_list_lock. All the callers have to do to get this right is make sure the cache_detail they pass in is allocated before calling sunrpc_init_cache_detail() and not freed till after calling sunrpc_destroy_cache_detail(). I think they all get that right. So I'm assuming this is a random memory scribble from somewhere else or something, unless it pops up again.... (The one thing I'm a little unsure of here is the list_empty(&cache_list) checks used to decide when to stop the cache_cleaner. But that's a separate problem, if it is a problem.) --b. > Code: 81 fb 20 eb 94 8a 0f 84 b8 00 00 00 e8 80 df 33 fa 48 8d 83 40 ff ff ff 48 8d 7b 10 48 89 05 8e 8e 13 06 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 e0 05 00 00 48 8d 6c 24 38 4c 8b 63 10 48 89 > RSP: 0018:ffffc90008e1fc48 EFLAGS: 00010206 > RAX: 0000000012e34a9a RBX: 00000000971a54c0 RCX: ffffffff87406dbb > RDX: ffff88804358a000 RSI: ffffffff87406e00 RDI: 00000000971a54d0 > RBP: 0000000000000100 R08: 0000000000000001 R09: 0000000000000003 > R10: 0000000000000100 R11: 0000000000000000 R12: 0000000000000100 > R13: dffffc0000000000 R14: ffff88803451b200 R15: ffff8880ae735600 > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000004ef310 CR3: 000000009ca1b000 CR4: 00000000001526e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > do_cache_clean+0xd/0xd0 net/sunrpc/cache.c:502 > process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 > kthread+0x3b5/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > Modules linked in: > ---[ end trace 4c54bbd0e20d734b ]--- > RIP: 0010:cache_clean+0x119/0x7f0 net/sunrpc/cache.c:444 > Code: 81 fb 20 eb 94 8a 0f 84 b8 00 00 00 e8 80 df 33 fa 48 8d 83 40 ff ff ff 48 8d 7b 10 48 89 05 8e 8e 13 06 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 e0 05 00 00 48 8d 6c 24 38 4c 8b 63 10 48 89 > RSP: 0018:ffffc90008e1fc48 EFLAGS: 00010206 > RAX: 0000000012e34a9a RBX: 00000000971a54c0 RCX: ffffffff87406dbb > RDX: ffff88804358a000 RSI: ffffffff87406e00 RDI: 00000000971a54d0 > RBP: 0000000000000100 R08: 0000000000000001 R09: 0000000000000003 > R10: 0000000000000100 R11: 0000000000000000 R12: 0000000000000100 > R13: dffffc0000000000 R14: ffff88803451b200 R15: ffff8880ae735600 > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000004ef310 CR3: 000000009ca1b000 CR4: 00000000001526e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > This report 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 issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
