FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
6.1.122-syzkaller #0 Tainted: G W
------------------------------------------------------
syz.3.231/5659 is trying to acquire lock:
ffffffff8d207278 ((console_sem).lock){-.-.}-{2:2}, at: down_trylock+0x1c/0xa0 kernel/locking/semaphore.c:139
but task is already holding lock:
ffff8880b8e3a9d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa8/0x140 kernel/sched/core.c:545
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&rq->__lock){-.-.}-{2:2}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
_raw_spin_lock_nested+0x2d/0x40 kernel/locking/spinlock.c:378
raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
raw_spin_rq_lock kernel/sched/sched.h:1355 [inline]
rq_lock kernel/sched/sched.h:1645 [inline]
task_fork_fair+0x5d/0x350 kernel/sched/fair.c:11877
sched_cgroup_fork+0x374/0x400 kernel/sched/core.c:4682
copy_process+0x2442/0x4060 kernel/fork.c:2383
kernel_clone+0x222/0x920 kernel/fork.c:2681
user_mode_thread+0x12e/0x190 kernel/fork.c:2757
rest_init+0x23/0x300 init/main.c:698
start_kernel+0x0/0x53f init/main.c:893
start_kernel+0x496/0x53f init/main.c:1140
secondary_startup_64_no_verify+0xcf/0xdb
-> #1 (&p->pi_lock){-.-.}-{2:2}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
try_to_wake_up+0xad/0x12e0 kernel/sched/core.c:4108
up+0x6e/0x90 kernel/locking/semaphore.c:191
__up_console_sem+0x11a/0x1e0 kernel/printk/printk.c:260
__console_unlock kernel/printk/printk.c:2697 [inline]
console_unlock+0x591/0x7c0 kernel/printk/printk.c:2908
vprintk_emit+0x523/0x740 kernel/printk/printk.c:2303
dev_vprintk_emit+0x2aa/0x323 drivers/base/core.c:4932
dev_printk_emit+0xd9/0x118 drivers/base/core.c:4943
_dev_warn+0x11e/0x165 drivers/base/core.c:4999
firmware_fallback_sysfs+0x674/0x940 drivers/base/firmware_loader/fallback.c:229
_request_firmware+0xcf0/0x12b0 drivers/base/firmware_loader/main.c:884
request_firmware_work_func+0x126/0x270 drivers/base/firmware_loader/main.c:1135
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
-> #0 ((console_sem).lock){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
down_trylock+0x1c/0xa0 kernel/locking/semaphore.c:139
__down_trylock_console_sem+0x105/0x250 kernel/printk/printk.c:243
console_trylock kernel/printk/printk.c:2650 [inline]
console_trylock_spinning kernel/printk/printk.c:1896 [inline]
vprintk_emit+0x1ee/0x740 kernel/printk/printk.c:2302
_printk+0xd1/0x111 kernel/printk/printk.c:2328
fail_dump lib/fault-inject.c:45 [inline]
should_fail_ex+0x387/0x4d0 lib/fault-inject.c:147
strncpy_from_user+0x32/0x360 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x6c/0x130 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
bpf_probe_read_compat_str+0xe4/0x180 kernel/trace/bpf_trace.c:306
bpf_prog_c1796171ffc7efef+0x35/0x37
bpf_dispatcher_nop_func include/linux/bpf.h:992 [inline]
__bpf_prog_run include/linux/filter.h:596 [inline]
bpf_prog_run include/linux/filter.h:610 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
bpf_trace_run4+0x3c3/0x470 kernel/trace/bpf_trace.c:2325
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x2128/0x4570 kernel/sched/core.c:6555
preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
irqentry_exit+0x53/0x80 kernel/entry/common.c:439
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
clear_page_erms+0x7/0x10 arch/x86/lib/clear_page_64.S:49
clear_page arch/x86/include/asm/page_64.h:58 [inline]
clear_highpage include/linux/highmem.h:242 [inline]
clear_highpage_kasan_tagged include/linux/highmem.h:252 [inline]
kernel_init_pages mm/page_alloc.c:1381 [inline]
post_alloc_hook+0x145/0x1b0 mm/page_alloc.c:2527
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x3731/0x38d0 mm/page_alloc.c:4328
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5605
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x91/0x1d0 mm/slab_common.c:1077
__do_kmalloc_node mm/slab_common.c:924 [inline]
__kmalloc_node+0x111/0x230 mm/slab_common.c:943
kmalloc_node include/linux/slab.h:589 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:716 [inline]
kvzalloc include/linux/slab.h:724 [inline]
__v4l2_ctrl_modify_dimensions+0x437/0xb50 drivers/media/v4l2-core/v4l2-ctrls-api.c:1004
v4l2_ctrl_modify_dimensions include/media/v4l2-ctrls.h:1005 [inline]
vivid_update_format_cap+0x148f/0x2230 drivers/media/test-drivers/vivid/vivid-vid-cap.c:480
vidioc_s_input+0x331/0x1560 drivers/media/test-drivers/vivid/vivid-vid-cap.c:1423
__video_do_ioctl+0xa3a/0xe30 drivers/media/v4l2-core/v4l2-ioctl.c:3037
video_usercopy+0xa79/0x10c0 drivers/media/v4l2-core/v4l2-ioctl.c:3384
v4l2_ioctl+0x181/0x1d0 drivers/media/v4l2-core/v4l2-dev.c:364
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
other info that might help us debug this:
Chain exists of:
(console_sem).lock --> &p->pi_lock --> &rq->__lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&rq->__lock);
lock(&p->pi_lock);
lock(&rq->__lock);
lock((console_sem).lock);
*** DEADLOCK ***
4 locks held by syz.3.231/5659:
#0: ffff88802a975918 (&dev->mutex#3){+.+.}-{3:3}, at: __video_do_ioctl+0x505/0xe30 drivers/media/v4l2-core/v4l2-ioctl.c:3005
#1: ffff88802a9706e0 (vivid_ctrls:1580:(hdl_user_gen)->_lock){+.+.}-{3:3}, at: v4l2_ctrl_lock include/media/v4l2-ctrls.h:564 [inline]
#1: ffff88802a9706e0 (vivid_ctrls:1580:(hdl_user_gen)->_lock){+.+.}-{3:3}, at: v4l2_ctrl_modify_dimensions include/media/v4l2-ctrls.h:1004 [inline]
#1: ffff88802a9706e0 (vivid_ctrls:1580:(hdl_user_gen)->_lock){+.+.}-{3:3}, at: vivid_update_format_cap+0x147f/0x2230 drivers/media/test-drivers/vivid/vivid-vid-cap.c:480
#2: ffff8880b8e3a9d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa8/0x140 kernel/sched/core.c:545
#3: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#3: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#3: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2283 [inline]
#3: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0x16a/0x470 kernel/trace/bpf_trace.c:2325
stack backtrace:
CPU: 0 PID: 5659 Comm: syz.3.231 Tainted: G W 6.1.122-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
down_trylock+0x1c/0xa0 kernel/locking/semaphore.c:139
__down_trylock_console_sem+0x105/0x250 kernel/printk/printk.c:243
console_trylock kernel/printk/printk.c:2650 [inline]
console_trylock_spinning kernel/printk/printk.c:1896 [inline]
vprintk_emit+0x1ee/0x740 kernel/printk/printk.c:2302
_printk+0xd1/0x111 kernel/printk/printk.c:2328
fail_dump lib/fault-inject.c:45 [inline]
should_fail_ex+0x387/0x4d0 lib/fault-inject.c:147
strncpy_from_user+0x32/0x360 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x6c/0x130 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
bpf_probe_read_compat_str+0xe4/0x180 kernel/trace/bpf_trace.c:306
bpf_prog_c1796171ffc7efef+0x35/0x37
bpf_dispatcher_nop_func include/linux/bpf.h:992 [inline]
__bpf_prog_run include/linux/filter.h:596 [inline]
bpf_prog_run include/linux/filter.h:610 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
bpf_trace_run4+0x3c3/0x470 kernel/trace/bpf_trace.c:2325
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x2128/0x4570 kernel/sched/core.c:6555
preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
irqentry_exit+0x53/0x80 kernel/entry/common.c:439
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:clear_page_erms+0x7/0x10 arch/x86/lib/clear_page_64.S:50
Code: 48 89 47 18 48 89 47 20 48 89 47 28 48 89 47 30 48 89 47 38 48 8d 7f 40 75 d9 90 c3 0f 1f 80 00 00 00 00 b9 00 10 00 00 31 c0 aa c3 66 0f 1f 44 00 00 89 c8 48 c1 e9 03 74 18 0f 1f 84 00 00
RSP: 0018:ffffc9000cb8f520 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000009 RCX: 0000000000000f40
RDX: ffff88804a1b5000 RSI: 000000000000004b RDI: ffff88804a1b50c0
RBP: 0000000000000200 R08: dffffc0000000000 R09: ffffed1009400000
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000001
R13: 0000000000000000 R14: ffffea0001280000 R15: 0000000000152dc0
clear_page arch/x86/include/asm/page_64.h:58 [inline]
clear_highpage include/linux/highmem.h:242 [inline]
clear_highpage_kasan_tagged include/linux/highmem.h:252 [inline]
kernel_init_pages mm/page_alloc.c:1381 [inline]
post_alloc_hook+0x145/0x1b0 mm/page_alloc.c:2527
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x3731/0x38d0 mm/page_alloc.c:4328
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5605
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x91/0x1d0 mm/slab_common.c:1077
__do_kmalloc_node mm/slab_common.c:924 [inline]
__kmalloc_node+0x111/0x230 mm/slab_common.c:943
kmalloc_node include/linux/slab.h:589 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:716 [inline]
kvzalloc include/linux/slab.h:724 [inline]
__v4l2_ctrl_modify_dimensions+0x437/0xb50 drivers/media/v4l2-core/v4l2-ctrls-api.c:1004
v4l2_ctrl_modify_dimensions include/media/v4l2-ctrls.h:1005 [inline]
vivid_update_format_cap+0x148f/0x2230 drivers/media/test-drivers/vivid/vivid-vid-cap.c:480
vidioc_s_input+0x331/0x1560 drivers/media/test-drivers/vivid/vivid-vid-cap.c:1423
__video_do_ioctl+0xa3a/0xe30 drivers/media/v4l2-core/v4l2-ioctl.c:3037
video_usercopy+0xa79/0x10c0 drivers/media/v4l2-core/v4l2-ioctl.c:3384
v4l2_ioctl+0x181/0x1d0 drivers/media/v4l2-core/v4l2-dev.c:364
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa7a1185d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa7a2013038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa7a1375fa0 RCX: 00007fa7a1185d29
RDX: 00000000200000c0 RSI: 00000000c0045627 RDI: 0000000000000003
RBP: 00007fa7a2013090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007fa7a1375fa0 R15: 00007ffeb0a9cb48
CPU: 0 PID: 5659 Comm: syz.3.231 Tainted: G W 6.1.122-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
fail_dump lib/fault-inject.c:52 [inline]
should_fail_ex+0x3a6/0x4d0 lib/fault-inject.c:147
strncpy_from_user+0x32/0x360 lib/strncpy_from_user.c:118
strncpy_from_user_nofault+0x6c/0x130 mm/maccess.c:186
bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
bpf_probe_read_compat_str+0xe4/0x180 kernel/trace/bpf_trace.c:306
bpf_prog_c1796171ffc7efef+0x35/0x37
bpf_dispatcher_nop_func include/linux/bpf.h:992 [inline]
__bpf_prog_run include/linux/filter.h:596 [inline]
bpf_prog_run include/linux/filter.h:610 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
bpf_trace_run4+0x3c3/0x470 kernel/trace/bpf_trace.c:2325
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x2128/0x4570 kernel/sched/core.c:6555
preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
irqentry_exit+0x53/0x80 kernel/entry/common.c:439
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:clear_page_erms+0x7/0x10 arch/x86/lib/clear_page_64.S:50
Code: 48 89 47 18 48 89 47 20 48 89 47 28 48 89 47 30 48 89 47 38 48 8d 7f 40 75 d9 90 c3 0f 1f 80 00 00 00 00 b9 00 10 00 00 31 c0 aa c3 66 0f 1f 44 00 00 89 c8 48 c1 e9 03 74 18 0f 1f 84 00 00
RSP: 0018:ffffc9000cb8f520 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000009 RCX: 0000000000000f40
RDX: ffff88804a1b5000 RSI: 000000000000004b RDI: ffff88804a1b50c0
RBP: 0000000000000200 R08: dffffc0000000000 R09: ffffed1009400000
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000001
R13: 0000000000000000 R14: ffffea0001280000 R15: 0000000000152dc0
clear_page arch/x86/include/asm/page_64.h:58 [inline]
clear_highpage include/linux/highmem.h:242 [inline]
clear_highpage_kasan_tagged include/linux/highmem.h:252 [inline]
kernel_init_pages mm/page_alloc.c:1381 [inline]
post_alloc_hook+0x145/0x1b0 mm/page_alloc.c:2527
prep_new_page mm/page_alloc.c:2539 [inline]
get_page_from_freelist+0x3731/0x38d0 mm/page_alloc.c:4328
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5605
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x91/0x1d0 mm/slab_common.c:1077
__do_kmalloc_node mm/slab_common.c:924 [inline]
__kmalloc_node+0x111/0x230 mm/slab_common.c:943
kmalloc_node include/linux/slab.h:589 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:716 [inline]
kvzalloc include/linux/slab.h:724 [inline]
__v4l2_ctrl_modify_dimensions+0x437/0xb50 drivers/media/v4l2-core/v4l2-ctrls-api.c:1004
v4l2_ctrl_modify_dimensions include/media/v4l2-ctrls.h:1005 [inline]
vivid_update_format_cap+0x148f/0x2230 drivers/media/test-drivers/vivid/vivid-vid-cap.c:480
vidioc_s_input+0x331/0x1560 drivers/media/test-drivers/vivid/vivid-vid-cap.c:1423
__video_do_ioctl+0xa3a/0xe30 drivers/media/v4l2-core/v4l2-ioctl.c:3037
video_usercopy+0xa79/0x10c0 drivers/media/v4l2-core/v4l2-ioctl.c:3384
v4l2_ioctl+0x181/0x1d0 drivers/media/v4l2-core/v4l2-dev.c:364
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa7a1185d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa7a2013038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa7a1375fa0 RCX: 00007fa7a1185d29
RDX: 00000000200000c0 RSI: 00000000c0045627 RDI: 0000000000000003
RBP: 00007fa7a2013090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007fa7a1375fa0 R15: 00007ffeb0a9cb48
----------------
Code disassembly (best guess):
0: 48 89 47 18 mov %rax,0x18(%rdi)
4: 48 89 47 20 mov %rax,0x20(%rdi)
8: 48 89 47 28 mov %rax,0x28(%rdi)
c: 48 89 47 30 mov %rax,0x30(%rdi)
10: 48 89 47 38 mov %rax,0x38(%rdi)
14: 48 8d 7f 40 lea 0x40(%rdi),%rdi
18: 75 d9 jne 0xfffffff3
1a: 90 nop
1b: c3 ret
1c: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
23: b9 00 10 00 00 mov $0x1000,%ecx
28: 31 c0 xor %eax,%eax
* 2a: f3 aa rep stos %al,%es:(%rdi) <-- trapping instruction
2c: c3 ret
2d: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
33: 89 c8 mov %ecx,%eax
35: 48 c1 e9 03 shr $0x3,%rcx
39: 74 18 je 0x53
3b: 0f .byte 0xf
3c: 1f (bad)
3d: 84 00 test %al,(%rax)