On 8/31/21 12:48 PM, Hao Xu wrote: > 在 2021/8/31 下午7:26, Pavel Begunkov 写道: >> On 8/31/21 12:05 PM, Hao Xu wrote: >>> 在 2021/8/31 下午5:42, Pavel Begunkov 写道: >>>> On 8/31/21 10:19 AM, Hao Xu wrote: >>>>> 在 2021/8/31 上午10:14, Jens Axboe 写道: >>>>>> On 8/30/21 2:45 PM, syzbot wrote: >>>>>>> syzbot has found a reproducer for the following issue on: >>>>>>> >>>>>>> HEAD commit: 93717cde744f Add linux-next specific files for 20210830 >>>>>>> git tree: linux-next >>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=15200fad300000 >>>>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=c643ef5289990dd1 >>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=f9704d1878e290eddf73 >>>>>>> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 >>>>>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=111f5f9d300000 >>>>>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1651a415300000 >>>>>>> >>>>>>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>>>>>> Reported-by: syzbot+f9704d1878e290eddf73@xxxxxxxxxxxxxxxxxxxxxxxxx >>>>>>> >>>>>>> general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN >>>>>>> KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] >>>>>>> CPU: 0 PID: 6548 Comm: syz-executor433 Not tainted 5.14.0-next-20210830-syzkaller #0 >>>>>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >>>>>>> RIP: 0010:sock_from_file+0x20/0x90 net/socket.c:505 >>>>>>> Code: f5 ff ff ff c3 0f 1f 44 00 00 41 54 53 48 89 fb e8 85 e9 62 fa 48 8d 7b 28 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 4f 45 31 e4 48 81 7b 28 80 f1 8a 8a 74 0c e8 58 e9 >>>>>>> RSP: 0018:ffffc90002caf8e8 EFLAGS: 00010206 >>>>>>> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 >>>>>>> RDX: 0000000000000005 RSI: ffffffff8713203b RDI: 0000000000000028 >>>>>>> RBP: ffff888019fc0780 R08: ffffffff899aee40 R09: ffffffff81e21978 >>>>>>> R10: 0000000000000027 R11: 0000000000000009 R12: dffffc0000000000 >>>>>>> R13: 1ffff110033f80f9 R14: 0000000000000003 R15: ffff888019fc0780 >>>>>>> FS: 00000000013b5300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 >>>>>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>>> CR2: 00000000004ae0f0 CR3: 000000001d355000 CR4: 00000000001506f0 >>>>>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>>>>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>>>>>> Call Trace: >>>>>>> io_sendmsg+0x98/0x640 fs/io_uring.c:4681 >>>>>>> io_issue_sqe+0x14de/0x6ba0 fs/io_uring.c:6578 >>>>>>> __io_queue_sqe+0x90/0xb50 fs/io_uring.c:6864 >>>>>>> io_req_task_submit+0xbf/0x1b0 fs/io_uring.c:2218 >>>>>>> tctx_task_work+0x166/0x610 fs/io_uring.c:2143 >>>>>>> task_work_run+0xdd/0x1a0 kernel/task_work.c:164 >>>>>>> tracehook_notify_signal include/linux/tracehook.h:212 [inline] >>>>>>> handle_signal_work kernel/entry/common.c:146 [inline] >>>>>>> exit_to_user_mode_loop kernel/entry/common.c:172 [inline] >>>>>>> exit_to_user_mode_prepare+0x256/0x290 kernel/entry/common.c:209 >>>>>>> __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] >>>>>>> syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302 >>>>>>> do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 >>>>>>> entry_SYSCALL_64_after_hwframe+0x44/0xae >>>>>>> RIP: 0033:0x43fd49 >>>>>> >>>>>> Hao, this is due to: >>>>>> >>>>>> commit a8295b982c46d4a7c259a4cdd58a2681929068a9 >>>>>> Author: Hao Xu <haoxu@xxxxxxxxxxxxxxxxx> >>>>>> Date: Fri Aug 27 17:46:09 2021 +0800 >>>>>> >>>>>> io_uring: fix failed linkchain code logic >>>>>> >>>>>> which causes some weirdly super long chains from that single sqe. >>>>>> Can you take a look, please? >>>>> Sure, I'm working on this. >>>> >>>> Ah, saw it after sending a patch. It's nothing too curious, just >>>> a small error in logic. More interesting that we don't have a >>>> test case covering it, we should definitely add something. >>>> >>> Saw your patch after coding my fix..😂 >>> Since my email client doesn't receive your patch(only saw it in >>> webpage https://lore.kernel.org/), I put my comment here: >> >> Hmm, does it happen often? I'll CC you > Uncommon, somestimes there is delay. >> >> >>>> fs/io_uring.c | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>>> index 473a977c7979..a531c7324ea8 100644 >>>> --- a/fs/io_uring.c >>>> +++ b/fs/io_uring.c >>>> @@ -6717,6 +6717,8 @@ static inline void io_queue_sqe(struct io_kiocb *req) >>>> if (likely(!(req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL)))) { >>>> __io_queue_sqe(req); >>>> } else if (req->flags & REQ_F_FAIL) { >>>> + /* fail all, we don't submit */ >>>> + req->flags &= ~REQ_F_HARDLINK; >>> maybe set REQ_F_LINK here? >> >> if (unlikely((req->flags & REQ_F_FAIL) && >> !(req->flags & REQ_F_HARDLINK))) { >> posted |= (req->link != NULL); >> io_fail_links(req); >> } >> >> The problem is hardlink, normal will be failed. But there is indeed >> a problem with both patches, >> >> if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) >> // kill linked > Yeah, if we don't have REQ_F_LINK, io_req_complete_post() won't go to > the disarm branch Ah, that's what you meant, right. Good catch! >> >> Will resend with some tests on top >> >> >>>> io_req_complete_failed(req, req->result); >>>> } else { >>>> int ret = io_req_prep_async(req); >> > -- Pavel Begunkov
