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Subjectpossible deadlock in __dev_queue_xmit (3)
From
Hello,

syzbot found the following crash on:

HEAD commit: 419593da Add linux-next specific files for 20191129
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14709712e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f4b95d6f8310863
dashboard link: https://syzkaller.appspot.com/bug?extid=3b165dac15094065651e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3b165dac15094065651e@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.4.0-next-20191129-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/2879 is trying to acquire lock:
ffff88809435b218 (&dev->qdisc_tx_busylock_key#71){+...}, at: spin_lock
include/linux/spinlock.h:338 [inline]
ffff88809435b218 (&dev->qdisc_tx_busylock_key#71){+...}, at: __dev_xmit_skb
net/core/dev.c:3644 [inline]
ffff88809435b218 (&dev->qdisc_tx_busylock_key#71){+...}, at:
__dev_queue_xmit+0x2dce/0x35c0 net/core/dev.c:3982

but task is already holding lock:
ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at: spin_lock
include/linux/spinlock.h:338 [inline]
ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at: __netif_tx_lock
include/linux/netdevice.h:3929 [inline]
ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at:
sch_direct_xmit+0x2e0/0xd30 net/sched/sch_generic.c:311

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&dev->qdisc_xmit_lock_key#312){+.-.}:
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
__netif_tx_lock include/linux/netdevice.h:3929 [inline]
sch_direct_xmit+0x2e0/0xd30 net/sched/sch_generic.c:311
__dev_xmit_skb net/core/dev.c:3621 [inline]
__dev_queue_xmit+0x270a/0x35c0 net/core/dev.c:3982
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
neigh_resolve_output net/core/neighbour.c:1490 [inline]
neigh_resolve_output+0x5c4/0x990 net/core/neighbour.c:1470
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
mld_sendpack+0x9c2/0xed0 net/ipv6/mcast.c:1682
mld_send_cr net/ipv6/mcast.c:1978 [inline]
mld_ifc_timer_expire+0x454/0x950 net/ipv6/mcast.c:2477
call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0x6c3/0x1790 kernel/time/timer.c:1786
__do_softirq+0x262/0x98c kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x19b/0x1e0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
slab_alloc mm/slab.c:3313 [inline]
__do_kmalloc mm/slab.c:3654 [inline]
__kmalloc+0x2b8/0x770 mm/slab.c:3665
kmalloc include/linux/slab.h:561 [inline]
tomoyo_realpath_from_path+0xc5/0x660 security/tomoyo/realpath.c:252
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_number_perm+0x1dd/0x520 security/tomoyo/file.c:723
tomoyo_file_ioctl+0x23/0x30 security/tomoyo/tomoyo.c:341
security_file_ioctl+0x77/0xc0 security/security.c:1409
ksys_ioctl+0x57/0xd0 fs/ioctl.c:747
__do_sys_ioctl fs/ioctl.c:756 [inline]
__se_sys_ioctl fs/ioctl.c:754 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&dev->qdisc_tx_busylock_key#71){+...}:
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
__dev_xmit_skb net/core/dev.c:3644 [inline]
__dev_queue_xmit+0x2dce/0x35c0 net/core/dev.c:3982
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
neigh_resolve_output net/core/neighbour.c:1490 [inline]
neigh_resolve_output+0x5c4/0x990 net/core/neighbour.c:1470
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ndisc_send_skb+0xf1f/0x1490 net/ipv6/ndisc.c:505
ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:647
ndisc_solicit+0x2ed/0x470 net/ipv6/ndisc.c:739
neigh_probe+0xd0/0x120 net/core/neighbour.c:1012
__neigh_event_send+0x3e3/0x17c0 net/core/neighbour.c:1172
neigh_event_send include/net/neighbour.h:445 [inline]
neigh_resolve_output+0x5ee/0x990 net/core/neighbour.c:1474
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1795
ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1815
icmpv6_push_pending_frames+0x34b/0x540 net/ipv6/icmp.c:285
icmp6_send+0x1a7f/0x1f90 net/ipv6/icmp.c:598
icmpv6_send+0xec/0x220 net/ipv6/ip6_icmp.c:43
ip6_link_failure+0x2b/0x530 net/ipv6/route.c:2641
dst_link_failure include/net/dst.h:419 [inline]
ip_tunnel_xmit+0x1738/0x2d0c net/ipv4/ip_tunnel.c:824
__gre_xmit+0x5e9/0x9a0 net/ipv4/ip_gre.c:448
erspan_xmit+0x912/0x28f0 net/ipv4/ip_gre.c:683
__netdev_start_xmit include/linux/netdevice.h:4442 [inline]
netdev_start_xmit include/linux/netdevice.h:4456 [inline]
xmit_one net/core/dev.c:3420 [inline]
dev_hard_start_xmit+0x1a3/0x9b0 net/core/dev.c:3436
sch_direct_xmit+0x372/0xd30 net/sched/sch_generic.c:313
__dev_xmit_skb net/core/dev.c:3660 [inline]
__dev_queue_xmit+0x1cc9/0x35c0 net/core/dev.c:3982
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
neigh_resolve_output net/core/neighbour.c:1490 [inline]
neigh_resolve_output+0x5c4/0x990 net/core/neighbour.c:1470
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
rawv6_send_hdrinc net/ipv6/raw.c:687 [inline]
rawv6_sendmsg+0x203b/0x3860 net/ipv6/raw.c:944
inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:639 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:659
sock_write_iter+0x27c/0x3e0 net/socket.c:991
call_write_iter include/linux/fs.h:1902 [inline]
aio_write+0x2f2/0x540 fs/aio.c:1580
__io_submit_one fs/aio.c:1812 [inline]
io_submit_one+0xfbd/0x2ec0 fs/aio.c:1859
__do_sys_io_submit fs/aio.c:1918 [inline]
__se_sys_io_submit fs/aio.c:1888 [inline]
__x64_sys_io_submit+0x1bd/0x540 fs/aio.c:1888
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&dev->qdisc_xmit_lock_key#312);
lock(&dev->qdisc_tx_busylock_key#71);
lock(&dev->qdisc_xmit_lock_key#312);
lock(&dev->qdisc_tx_busylock_key#71);

*** DEADLOCK ***

12 locks held by syz-executor.3/2879:
#0: ffffffff891ad880 (rcu_read_lock){....}, at: l3mdev_l3_out
include/net/l3mdev.h:179 [inline]
#0: ffffffff891ad880 (rcu_read_lock){....}, at: l3mdev_ip6_out
include/net/l3mdev.h:200 [inline]
#0: ffffffff891ad880 (rcu_read_lock){....}, at: rawv6_send_hdrinc
net/ipv6/raw.c:677 [inline]
#0: ffffffff891ad880 (rcu_read_lock){....}, at:
rawv6_sendmsg+0x1e28/0x3860 net/ipv6/raw.c:944
#1: ffffffff891ad840 (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect
include/net/lwtunnel.h:92 [inline]
#1: ffffffff891ad840 (rcu_read_lock_bh){....}, at:
ip6_finish_output2+0x214/0x25c0 net/ipv6/ip6_output.c:102
#2: ffffffff891ad840 (rcu_read_lock_bh){....}, at:
__dev_queue_xmit+0x20a/0x35c0 net/core/dev.c:3948
#3: ffff88809435b138 (&dev->qdisc_running_key#128){+...}, at:
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
#4: ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at: spin_lock
include/linux/spinlock.h:338 [inline]
#4: ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at:
__netif_tx_lock include/linux/netdevice.h:3929 [inline]
#4: ffff8880a9b9cc98 (&dev->qdisc_xmit_lock_key#312){+.-.}, at:
sch_direct_xmit+0x2e0/0xd30 net/sched/sch_generic.c:311
#5: ffffffff891ad880 (rcu_read_lock){....}, at: icmpv6_send+0x0/0x220
net/ipv6/ip6_icmp.c:31
#6: ffff88806e2194e0 (k-slock-AF_INET6){+.-.}, at: spin_trylock
include/linux/spinlock.h:348 [inline]
#6: ffff88806e2194e0 (k-slock-AF_INET6){+.-.}, at: icmpv6_xmit_lock
net/ipv6/icmp.c:117 [inline]
#6: ffff88806e2194e0 (k-slock-AF_INET6){+.-.}, at: icmp6_send+0xde8/0x1f90
net/ipv6/icmp.c:519
#7: ffffffff891ad880 (rcu_read_lock){....}, at: icmp6_send+0x13cd/0x1f90
net/ipv6/icmp.c:579
#8: ffffffff891ad840 (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect
include/net/lwtunnel.h:92 [inline]
#8: ffffffff891ad840 (rcu_read_lock_bh){....}, at:
ip6_finish_output2+0x214/0x25c0 net/ipv6/ip6_output.c:102
#9: ffffffff891ad880 (rcu_read_lock){....}, at: ip6_nd_hdr
net/ipv6/ndisc.c:463 [inline]
#9: ffffffff891ad880 (rcu_read_lock){....}, at:
ndisc_send_skb+0x7fe/0x1490 net/ipv6/ndisc.c:499
#10: ffffffff891ad840 (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect
include/net/lwtunnel.h:92 [inline]
#10: ffffffff891ad840 (rcu_read_lock_bh){....}, at:
ip6_finish_output2+0x214/0x25c0 net/ipv6/ip6_output.c:102
#11: ffffffff891ad840 (rcu_read_lock_bh){....}, at:
__dev_queue_xmit+0x20a/0x35c0 net/core/dev.c:3948

stack backtrace:
CPU: 0 PID: 2879 Comm: syz-executor.3 Not tainted
5.4.0-next-20191129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685
check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
__dev_xmit_skb net/core/dev.c:3644 [inline]
__dev_queue_xmit+0x2dce/0x35c0 net/core/dev.c:3982
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
neigh_resolve_output net/core/neighbour.c:1490 [inline]
neigh_resolve_output+0x5c4/0x990 net/core/neighbour.c:1470
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ndisc_send_skb+0xf1f/0x1490 net/ipv6/ndisc.c:505
ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:647
ndisc_solicit+0x2ed/0x470 net/ipv6/ndisc.c:739
neigh_probe+0xd0/0x120 net/core/neighbour.c:1012
__neigh_event_send+0x3e3/0x17c0 net/core/neighbour.c:1172
neigh_event_send include/net/neighbour.h:445 [inline]
neigh_resolve_output+0x5ee/0x990 net/core/neighbour.c:1474
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1795
ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1815
icmpv6_push_pending_frames+0x34b/0x540 net/ipv6/icmp.c:285
icmp6_send+0x1a7f/0x1f90 net/ipv6/icmp.c:598
icmpv6_send+0xec/0x220 net/ipv6/ip6_icmp.c:43
ip6_link_failure+0x2b/0x530 net/ipv6/route.c:2641
dst_link_failure include/net/dst.h:419 [inline]
ip_tunnel_xmit+0x1738/0x2d0c net/ipv4/ip_tunnel.c:824
__gre_xmit+0x5e9/0x9a0 net/ipv4/ip_gre.c:448
erspan_xmit+0x912/0x28f0 net/ipv4/ip_gre.c:683
__netdev_start_xmit include/linux/netdevice.h:4442 [inline]
netdev_start_xmit include/linux/netdevice.h:4456 [inline]
xmit_one net/core/dev.c:3420 [inline]
dev_hard_start_xmit+0x1a3/0x9b0 net/core/dev.c:3436
sch_direct_xmit+0x372/0xd30 net/sched/sch_generic.c:313
__dev_xmit_skb net/core/dev.c:3660 [inline]
__dev_queue_xmit+0x1cc9/0x35c0 net/core/dev.c:3982
dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
neigh_resolve_output net/core/neighbour.c:1490 [inline]
neigh_resolve_output+0x5c4/0x990 net/core/neighbour.c:1470
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x109a/0x25c0 net/ipv6/ip6_output.c:116
__ip6_finish_output+0x444/0xaa0 net/ipv6/ip6_output.c:142
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x25e/0x880 net/ipv6/ip6_output.c:175
dst_output include/net/dst.h:436 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
rawv6_send_hdrinc net/ipv6/raw.c:687 [inline]
rawv6_sendmsg+0x203b/0x3860 net/ipv6/raw.c:944
inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:639 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:659
sock_write_iter+0x27c/0x3e0 net/socket.c:991
call_write_iter include/linux/fs.h:1902 [inline]
aio_write+0x2f2/0x540 fs/aio.c:1580
__io_submit_one fs/aio.c:1812 [inline]
io_submit_one+0xfbd/0x2ec0 fs/aio.c:1859
__do_sys_io_submit fs/aio.c:1918 [inline]
__se_sys_io_submit fs/aio.c:1888 [inline]
__x64_sys_io_submit+0x1bd/0x540 fs/aio.c:1888
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a679
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fbd60c44c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a679
RDX: 0000000020356ff0 RSI: 0000000000000001 RDI: 00007fbd60c24000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbd60c456d4
R13: 00000000004c1d83 R14: 00000000004d6060 R15: 00000000ffffffff
syz-executor.3 (2879) used greatest stack depth: 20000 bytes left


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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