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 >> 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 Will resend with some tests on top >> io_req_complete_failed(req, req->result); >> } else { >> int ret = io_req_prep_async(req); -- Pavel Begunkov
