On Mon, 9 Aug 2021 at 19:33, Shoaib Rao <rao.shoaib@xxxxxxxxxx> wrote: > > This seems like a false positive. 1) The function will not sleep because > it only calls copy routine if the byte is present. 2). There is no > difference between this new call and the older calls in > unix_stream_read_generic(). Hi Shoaib, Thanks for looking into this. Do you have any ideas on how to fix this tool's false positive? Tools with false positives are order of magnitude less useful than tools w/o false positives. E.g. do we turn it off on syzbot? But I don't remember any other false positives from "sleeping function called from invalid context" checker... > On 8/8/21 4:38 PM, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: c2eecaa193ff pktgen: Remove redundant clone_skb override > > git tree: net-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e3a69e300000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=aba0c23f8230e048 > > dashboard link: https://syzkaller.appspot.com/bug?extid=8760ca6c1ee783ac4abd > > 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=15c5b104300000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10062aaa300000 > > > > The issue was bisected to: > > > > commit 314001f0bf927015e459c9d387d62a231fe93af3 > > Author: Rao Shoaib <rao.shoaib@xxxxxxxxxx> > > Date: Sun Aug 1 07:57:07 2021 +0000 > > > > af_unix: Add OOB support > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10765f8e300000 > > final oops: https://syzkaller.appspot.com/x/report.txt?x=12765f8e300000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=14765f8e300000 > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+8760ca6c1ee783ac4abd@xxxxxxxxxxxxxxxxxxxxxxxxx > > Fixes: 314001f0bf92 ("af_unix: Add OOB support") > > > > BUG: sleeping function called from invalid context at lib/iov_iter.c:619 > > in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 8443, name: syz-executor700 > > 2 locks held by syz-executor700/8443: > > #0: ffff888028fa0d00 (&u->iolock){+.+.}-{3:3}, at: unix_stream_read_generic+0x16c6/0x2190 net/unix/af_unix.c:2501 > > #1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] > > #1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: unix_stream_read_generic+0x16d0/0x2190 net/unix/af_unix.c:2502 > > Preemption disabled at: > > [<0000000000000000>] 0x0 > > CPU: 1 PID: 8443 Comm: syz-executor700 Not tainted 5.14.0-rc3-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:88 [inline] > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 > > ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9154 > > __might_fault+0x6e/0x180 mm/memory.c:5258 > > _copy_to_iter+0x199/0x1600 lib/iov_iter.c:619 > > copy_to_iter include/linux/uio.h:139 [inline] > > simple_copy_to_iter+0x4c/0x70 net/core/datagram.c:519 > > __skb_datagram_iter+0x10f/0x770 net/core/datagram.c:425 > > skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:533 > > skb_copy_datagram_msg include/linux/skbuff.h:3620 [inline] > > unix_stream_read_actor+0x78/0xc0 net/unix/af_unix.c:2701 > > unix_stream_recv_urg net/unix/af_unix.c:2433 [inline] > > unix_stream_read_generic+0x17cd/0x2190 net/unix/af_unix.c:2504 > > unix_stream_recvmsg+0xb1/0xf0 net/unix/af_unix.c:2717 > > sock_recvmsg_nosec net/socket.c:944 [inline] > > sock_recvmsg net/socket.c:962 [inline] > > sock_recvmsg net/socket.c:958 [inline] > > ____sys_recvmsg+0x2c4/0x600 net/socket.c:2622 > > ___sys_recvmsg+0x127/0x200 net/socket.c:2664 > > do_recvmmsg+0x24d/0x6d0 net/socket.c:2758 > > __sys_recvmmsg net/socket.c:2837 [inline] > > __do_sys_recvmmsg net/socket.c:2860 [inline] > > __se_sys_recvmmsg net/socket.c:2853 [inline] > > __x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2853 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > RIP: 0033:0x43ef39 > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > RSP: 002b:00007ffca8776d68 EFLAGS: 00000246 ORIG_RAX: 000000000000012b > > RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ef39 > > RDX: 0000000000000700 RSI: 0000000020001140 RDI: 0000000000000004 > > RBP: 0000000000402f20 R08: 0000000000000000 R09: 0000000000400488 > > R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000402fb0 > > R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488 > > > > ============================= > > [ BUG: Invalid wait context ] > > 5.14.0-rc3-syzkaller #0 Tainted: G W > > ----------------------------- > > syz-executor700/8443 is trying to lock: > > ffff8880212b6a28 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0xa3/0x180 mm/memory.c:5260 > > other info that might help us debug this: > > context-{4:4} > > 2 locks held by syz-executor700/8443: > > #0: ffff888028fa0d00 (&u->iolock){+.+.}-{3:3}, at: unix_stream_read_generic+0x16c6/0x2190 net/unix/af_unix.c:2501 > > #1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] > > #1: ffff888028fa0df0 (&u->lock){+.+.}-{2:2}, at: unix_stream_read_generic+0x16d0/0x2190 net/unix/af_unix.c:2502 > > stack backtrace: > > CPU: 1 PID: 8443 Comm: syz-executor700 Tainted: G W 5.14.0-rc3-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:88 [inline] > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 > > print_lock_invalid_wait_context kernel/locking/lockdep.c:4666 [inline] > > check_wait_context kernel/locking/lockdep.c:4727 [inline] > > __lock_acquire.cold+0x213/0x3ab kernel/locking/lockdep.c:4965 > > lock_acquire kernel/locking/lockdep.c:5625 [inline] > > lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 > > __might_fault mm/memory.c:5261 [inline] > > __might_fault+0x106/0x180 mm/memory.c:5246 > > _copy_to_iter+0x199/0x1600 lib/iov_iter.c:619 > > copy_to_iter include/linux/uio.h:139 [inline] > > simple_copy_to_iter+0x4c/0x70 net/core/datagram.c:519 > > __skb_datagram_iter+0x10f/0x770 net/core/datagram.c:425 > > skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:533 > > skb_copy_datagram_msg include/linux/skbuff.h:3620 [inline] > > unix_stream_read_actor+0x78/0xc0 net/unix/af_unix.c:2701 > > unix_stream_recv_urg net/unix/af_unix.c:2433 [inline] > > unix_stream_read_generic+0x17cd/0x2190 net/unix/af_unix.c:2504 > > unix_stream_recvmsg+0xb1/0xf0 net/unix/af_unix.c:2717 > > sock_recvmsg_nosec net/socket.c:944 [inline] > > sock_recvmsg net/socket.c:962 [inline] > > sock_recvmsg net/socket.c:958 [inline] > > ____sys_recvmsg+0x2c4/0x600 net/socket.c:2622 > > ___sys_recvmsg+0x127/0x200 net/socket.c:2664 > > do_recvmmsg+0x24d/0x6d0 net/socket.c:2758 > > __sys_recvmmsg net/socket.c:2837 [inline] > > __do_sys_recvmmsg net/socket.c:2860 [inline] > > __se_sys_recvmmsg net/socket.c:2853 [inline] > > __x64_sys_recvmmsg+0x20b/0x260 net/socket.c:2853 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > RIP: 0033:0x43ef39 > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > RSP: 002b:00007ffca8776d68 EFLAGS: 00000246 ORIG_RAX: 000000000000012b > > RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ef39 > > RDX: 0000000000000700 RSI: 0000000020001140 RDI: 0000000000000004 > > RBP: 0000000000402f20 R08: 0000000000000000 R09: 0000000000400488 > > R10: 0000000000000007 R11: 0000000000000246 R12: 0000 > > > > > > --- > > 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. > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > syzbot can test patches for this issue, 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@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/0c106e6c-672f-474e-5815-97b65596139d%40oracle.com.
