syzbot
INFO: task hung in tcp_sendmsg
Status:
premoderation: reported on 2026/09/15 07:42
Reported-by: syzbot+1e7796b74913a0423dc7@syzkaller.appspotmail.com
First crash: 5d01h, last: 5d01h
Sample crash report:
INFO: task syz.0.120:674 blocked for more than 123 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.120 state:D stack:0 pid:674 tgid:671 ppid:293 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:6063 [inline]
__schedule+0x1496/0x20b0 kernel/sched/core.c:7883
__schedule_loop kernel/sched/core.c:7960 [inline]
schedule+0xc5/0x240 kernel/sched/core.c:7975
__lock_sock net/core/sock.c:3088 [inline]
lock_sock_nested+0x17e/0x2a0 net/core/sock.c:3670
lock_sock include/net/sock.h:1678 [inline]
sk_stream_wait_memory+0x905/0xf80 net/core/stream.c:145
tcp_sendmsg_locked+0x134c/0x4ac0 net/ipv4/tcp.c:1322
tcp_sendmsg+0x3e/0xd0 net/ipv4/tcp.c:1365
inet_sendmsg+0xb7/0x120 net/ipv4/af_inet.c:858
sock_sendmsg_nosec net/socket.c:713 [inline]
__sock_sendmsg net/socket.c:727 [inline]
__sys_sendto+0x5d8/0x6e0 net/socket.c:2197
__do_sys_sendto net/socket.c:2204 [inline]
__se_sys_sendto net/socket.c:2200 [inline]
__x64_sys_sendto+0xe9/0x100 net/socket.c:2200
x64_sys_call+0x2c2c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:45
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fe8a299e159
RSP: 002b:00007fe8a37a0028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fe8a2c25fa0 RCX: 00007fe8a299e159
RDX: ffffffffffffff94 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007fe8a2a3503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe8a2c26038 R14: 00007fe8a2c25fa0 R15: 00007ffe4c1f9c48
</TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 f62b9527b829eee6a2ac5cf651ba087b59645d0c
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
__dump_stack+0x21/0x30 lib/dump_stack.c:94
dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
dump_stack+0x19/0x20 lib/dump_stack.c:129
nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
watchdog+0xe45/0xf90 kernel/hung_task.c:423
kthread+0x2c4/0x360 kernel/kthread.c:389
ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 17 Comm: ksoftirqd/0 Not tainted syzkaller #0 f62b9527b829eee6a2ac5cf651ba087b59645d0c
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:clear_page_erms+0xb/0x30 arch/x86/lib/clear_page_64.S:50
Code: 48 8d 7f 40 75 d9 90 c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa b9 00 10 00 00 31 c0 <f3> aa e9 8e 7c 03 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000116dd8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff92000022dc0 RCX: 0000000000000f40
RDX: ffff88813f37d000 RSI: 0000000000000001 RDI: ffff88813f37d0c0
RBP: ffffc90000116e90 R08: ffffffff87e4667f R09: 0000000000000000
R10: ffffed1027e6fa00 R11: fffffbfff0fc8cd0 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc9c1dae4c0 CR3: 000000010af0c000 CR4: 00000000003526b0
Call Trace:
<TASK>
prep_new_page+0x2d/0x180 mm/page_alloc.c:1871
get_page_from_freelist+0x4aea/0x4ba0 mm/page_alloc.c:3948
__alloc_pages_noprof+0x35a/0x7e0 mm/page_alloc.c:5315
alloc_slab_page+0x6b/0x1e0 mm/slub.c:-1
allocate_slab+0x69/0x430 mm/slub.c:2687
new_slab mm/slub.c:2741 [inline]
___slab_alloc+0x591/0x8c0 mm/slub.c:3934
__slab_alloc mm/slub.c:4025 [inline]
__slab_alloc_node mm/slub.c:4078 [inline]
slab_alloc_node mm/slub.c:4239 [inline]
kmem_cache_alloc_noprof+0x290/0x410 mm/slub.c:4260
skb_clone+0x21d/0x470 net/core/skbuff.c:2084
deliver_clone net/bridge/br_forward.c:125 [inline]
br_flood+0x650/0x720 net/bridge/br_forward.c:246
br_handle_frame_finish+0x1157/0x1620 net/bridge/br_input.c:215
nf_hook_bridge_pre net/bridge/br_input.c:301 [inline]
br_handle_frame+0x5a5/0xba0 net/bridge/br_input.c:424
__netif_receive_skb_core+0xfc1/0x3a70 net/core/dev.c:5695
__netif_receive_skb_one_core net/core/dev.c:5799 [inline]
__netif_receive_skb net/core/dev.c:5914 [inline]
process_backlog+0x40b/0xaf0 net/core/dev.c:6250
__napi_poll+0xd0/0x600 net/core/dev.c:6901
napi_poll net/core/dev.c:6970 [inline]
net_rx_action+0x5dc/0xd70 net/core/dev.c:7092
handle_softirqs+0x1aa/0x620 kernel/softirq.c:621
run_ksoftirqd+0x20/0x30 kernel/softirq.c:999
smpboot_thread_fn+0x486/0x8b0 kernel/smpboot.c:164
kthread+0x2c4/0x360 kernel/kthread.c:389
ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
net_ratelimit: 135636 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:92:4e:7c:3c:8b:b3, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:92:4e:7c:3c:8b:b3, vlan:0)
net_ratelimit: 156714 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:92:4e:7c:3c:8b:b3, vlan:0)
* Struck through repros no longer work on HEAD.