Unknown ioctl 1074025690 ================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic64_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:1515 [inline] BUG: KASAN: use-after-free in atomic_long_try_cmpxchg_acquire include/asm-generic/atomic-long.h:443 [inline] BUG: KASAN: use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:173 [inline] BUG: KASAN: use-after-free in mutex_lock+0x7f/0xe0 kernel/locking/mutex.c:298 Write of size 8 at addr ffff888123766040 by task syz.2.4302/17595 CPU: 0 PID: 17595 Comm: syz.2.4302 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x280/0x290 mm/kasan/generic.c:189 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic64_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:1515 [inline] atomic_long_try_cmpxchg_acquire include/asm-generic/atomic-long.h:443 [inline] __mutex_trylock_fast kernel/locking/mutex.c:173 [inline] mutex_lock+0x7f/0xe0 kernel/locking/mutex.c:298 steam_input_open+0x91/0x160 drivers/hid/hid-steam.c:297 input_open_device+0x14c/0x2a0 drivers/input/input.c:635 evdev_open_device drivers/input/evdev.c:400 [inline] evdev_open+0x4d2/0x5e0 drivers/input/evdev.c:487 chrdev_open+0x597/0x670 fs/char_dev.c:414 do_dentry_open+0x793/0x1090 fs/open.c:819 vfs_open+0x73/0x80 fs/open.c:942 do_open fs/namei.c:3391 [inline] path_openat+0x27ad/0x3160 fs/namei.c:3509 do_filp_open+0x1b3/0x3e0 fs/namei.c:3536 do_sys_openat2+0x14c/0x6d0 fs/open.c:1217 do_sys_open fs/open.c:1233 [inline] __do_sys_openat fs/open.c:1249 [inline] __se_sys_openat fs/open.c:1244 [inline] __x64_sys_openat+0x136/0x160 fs/open.c:1244 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fb56fdde590 Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 49 94 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 9c 94 02 00 8b 44 RSP: 002b:00007fb56e847b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000000a0400 RCX: 00007fb56fdde590 RDX: 00000000000a0400 RSI: 00007fb56e847c10 RDI: 00000000ffffff9c RBP: 00007fb56e847c10 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd R13: 00007fb570027038 R14: 00007fb570026fa0 R15: 00007ffec4d67038 Allocated by task 15050: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] ____kasan_kmalloc mm/kasan/common.c:509 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] kmem_cache_alloc_trace+0x184/0x2e0 mm/slub.c:2979 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:664 [inline] fuse_writepage_args_alloc fs/fuse/file.c:2002 [inline] fuse_writepages_fill+0x88e/0x1e10 fs/fuse/file.c:2288 write_cache_pages+0x76b/0xc80 mm/page-writeback.c:2274 fuse_writepages+0x1cf/0x310 fs/fuse/file.c:2358 do_writepages+0x12a/0x270 mm/page-writeback.c:2380 __filemap_fdatawrite_range+0x2bc/0x360 mm/filemap.c:427 file_write_and_wait_range+0x8c/0x110 mm/filemap.c:766 fuse_fsync+0x28a/0x1540 fs/fuse/file.c:616 vfs_fsync_range+0x190/0x1a0 fs/sync.c:202 generic_write_sync include/linux/fs.h:2920 [inline] generic_file_write_iter+0x17c/0x1d0 mm/filemap.c:3674 fuse_cache_write_iter fs/fuse/file.c:1369 [inline] fuse_file_write_iter+0xedc/0x1db0 fs/fuse/file.c:1714 do_iter_readv_writev+0x491/0x600 fs/read_write.c:-1 do_iter_write+0x189/0x630 fs/read_write.c:866 vfs_writev+0x293/0x4f0 fs/read_write.c:939 do_writev+0x14a/0x2b0 fs/read_write.c:982 __do_sys_writev fs/read_write.c:1055 [inline] __se_sys_writev fs/read_write.c:1052 [inline] __x64_sys_writev+0x7d/0x90 fs/read_write.c:1052 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 16687: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1600 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626 slab_free mm/slub.c:3208 [inline] kfree+0xc0/0x270 mm/slub.c:4196 skb_free_head net/core/skbuff.c:606 [inline] skb_release_data+0x532/0x670 net/core/skbuff.c:626 skb_release_all net/core/skbuff.c:680 [inline] __kfree_skb net/core/skbuff.c:694 [inline] kfree_skb+0xb9/0x2f0 net/core/skbuff.c:713 unix_release_sock+0x82c/0xad0 net/unix/af_unix.c:563 unix_release+0x4e/0x80 net/unix/af_unix.c:869 __sock_release net/socket.c:597 [inline] sock_close+0xe0/0x270 net/socket.c:1286 __fput+0x2fb/0x770 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa4f/0x2480 kernel/exit.c:872 do_group_exit+0x141/0x310 kernel/exit.c:986 get_signal+0xf7d/0x12e0 kernel/signal.c:2793 arch_do_signal_or_restart+0xbf/0x10f0 arch/x86/kernel/signal.c:805 handle_signal_work kernel/entry/common.c:145 [inline] exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 kvfree_call_rcu+0x10c/0x620 kernel/rcu/tree.c:3539 drop_sysctl_table+0x2ef/0x410 fs/proc/proc_sysctl.c:1684 drop_sysctl_table+0x2de/0x410 fs/proc/proc_sysctl.c:1687 drop_sysctl_table+0x2de/0x410 fs/proc/proc_sysctl.c:1687 unregister_sysctl_table+0x75/0x120 fs/proc/proc_sysctl.c:1722 unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:127 netfilter_log_sysctl_exit net/netfilter/nf_log.c:524 [inline] nf_log_net_exit+0x60/0xc0 net/netfilter/nf_log.c:565 ops_exit_list net/core/net_namespace.c:185 [inline] cleanup_net+0x586/0xb70 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Second to last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 __call_rcu kernel/rcu/tree.c:2980 [inline] call_rcu+0x10e/0x1050 kernel/rcu/tree.c:3054 fib6_info_release include/net/ip6_fib.h:346 [inline] fib6_del_route net/ipv6/ip6_fib.c:1996 [inline] fib6_del+0xc50/0xf60 net/ipv6/ip6_fib.c:2029 fib6_clean_node+0x296/0x520 net/ipv6/ip6_fib.c:2191 fib6_walk_continue+0x4fc/0x700 net/ipv6/ip6_fib.c:2113 fib6_walk+0x153/0x290 net/ipv6/ip6_fib.c:2161 fib6_clean_tree net/ipv6/ip6_fib.c:2241 [inline] __fib6_clean_all net/ipv6/ip6_fib.c:2257 [inline] fib6_clean_all+0x16a/0x230 net/ipv6/ip6_fib.c:2268 rt6_sync_down_dev net/ipv6/route.c:4795 [inline] rt6_disable_ip+0x119/0x6a0 net/ipv6/route.c:4800 addrconf_ifdown+0x144/0x1800 net/ipv6/addrconf.c:3788 addrconf_notify+0x3bd/0xe90 net/ipv6/addrconf.c:-1 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410 call_netdevice_notifiers_info net/core/dev.c:2054 [inline] call_netdevice_notifiers_extack net/core/dev.c:2066 [inline] call_netdevice_notifiers net/core/dev.c:2080 [inline] __dev_notify_flags+0x28f/0x500 net/core/dev.c:-1 dev_change_flags+0xe8/0x1a0 net/core/dev.c:8610 do_setlink+0xbb4/0x3ab0 net/core/rtnetlink.c:2732 rtnl_group_changelink net/core/rtnetlink.c:3251 [inline] __rtnl_newlink net/core/rtnetlink.c:3420 [inline] rtnl_newlink+0xd32/0x1640 net/core/rtnetlink.c:3530 rtnetlink_rcv_msg+0x9db/0xb90 net/core/rtnetlink.c:5610 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5628 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x88d/0xb30 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2376 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2430 __sys_sendmsg net/socket.c:2459 [inline] __do_sys_sendmsg net/socket.c:2468 [inline] __se_sys_sendmsg net/socket.c:2466 [inline] __x64_sys_sendmsg+0x1e2/0x2a0 net/socket.c:2466 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff888123766000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 64 bytes inside of 512-byte region [ffff888123766000, ffff888123766200) The buggy address belongs to the page: page:ffffea00048dd900 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888123765800 pfn:0x123764 head:ffffea00048dd900 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 ffffea0004589408 ffffea0004af6a08 ffff888100043080 raw: ffff888123765800 000000000010000d 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 3746, ts 173753332567, free_ts 173232585327 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc_trace+0x1b3/0x2e0 mm/slub.c:2977 kmalloc include/linux/slab.h:552 [inline] kmalloc_array include/linux/slab.h:591 [inline] rtnl_newlink+0x103/0x1640 net/core/rtnetlink.c:3526 rtnetlink_rcv_msg+0x9db/0xb90 net/core/rtnetlink.c:5610 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2503 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5628 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x876/0xa40 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x88d/0xb30 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] __sys_sendto+0x41d/0x580 net/socket.c:2006 __do_sys_sendto net/socket.c:2018 [inline] __se_sys_sendto net/socket.c:2014 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2014 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] free_pcp_prepare mm/page_alloc.c:1421 [inline] free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336 free_unref_page mm/page_alloc.c:3391 [inline] free_the_page mm/page_alloc.c:5429 [inline] __free_pages+0x14b/0x380 mm/page_alloc.c:5440 __vunmap+0x84d/0x9d0 mm/vmalloc.c:2307 __vfree mm/vmalloc.c:2356 [inline] vfree+0x61/0x90 mm/vmalloc.c:2387 kcov_put kernel/kcov.c:408 [inline] kcov_close+0x2b/0x50 kernel/kcov.c:510 __fput+0x2fb/0x770 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa4f/0x2480 kernel/exit.c:872 do_group_exit+0x141/0x310 kernel/exit.c:986 __do_sys_exit_group kernel/exit.c:997 [inline] __se_sys_exit_group kernel/exit.c:995 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:995 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Memory state around the buggy address: ffff888123765f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888123765f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888123766000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888123766080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888123766100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== general protection fault, probably for non-canonical address 0xdffffc0000000213: 0000 [#1] PREEMPT SMP KASAN KASAN: probably user-memory-access in range [0x0000000000001098-0x000000000000109f] CPU: 1 PID: 17595 Comm: syz.2.4302 Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025 RIP: 0010:steam_send_report+0x66/0x310 drivers/hid/hid-steam.c:172 Code: 80 3c 18 00 74 12 4c 89 f7 e8 c6 34 3f fe 48 ba 00 00 00 00 00 fc ff df 4d 8b 26 49 8d 9c 24 98 10 00 00 48 89 d8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 df e8 9c 34 3f fe 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90000f77668 EFLAGS: 00010202 RAX: 0000000000000213 RBX: 0000000000001098 RCX: 0000000000000282 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff888123766030 RBP: ffffc90000f776b0 R08: dffffc0000000000 R09: fffff520001eeec9 R10: fffff520001eeec9 R11: 1ffff920001eeec8 R12: 0000000000000000 R13: 1ffff920001eeed8 R14: ffff888123766030 R15: ffffc90000f776e0 FS: 00007fb56e8486c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000124f02000 CR4: 00000000003526a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: steam_send_report_byte drivers/hid/hid-steam.c:212 [inline] steam_set_lizard_mode drivers/hid/hid-steam.c:285 [inline] steam_input_open+0xde/0x160 drivers/hid/hid-steam.c:299 input_open_device+0x14c/0x2a0 drivers/input/input.c:635 evdev_open_device drivers/input/evdev.c:400 [inline] evdev_open+0x4d2/0x5e0 drivers/input/evdev.c:487 chrdev_open+0x597/0x670 fs/char_dev.c:414 do_dentry_open+0x793/0x1090 fs/open.c:819 vfs_open+0x73/0x80 fs/open.c:942 do_open fs/namei.c:3391 [inline] path_openat+0x27ad/0x3160 fs/namei.c:3509 do_filp_open+0x1b3/0x3e0 fs/namei.c:3536 do_sys_openat2+0x14c/0x6d0 fs/open.c:1217 do_sys_open fs/open.c:1233 [inline] __do_sys_openat fs/open.c:1249 [inline] __se_sys_openat fs/open.c:1244 [inline] __x64_sys_openat+0x136/0x160 fs/open.c:1244 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fb56fdde590 Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 49 94 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 9c 94 02 00 8b 44 RSP: 002b:00007fb56e847b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000000a0400 RCX: 00007fb56fdde590 RDX: 00000000000a0400 RSI: 00007fb56e847c10 RDI: 00000000ffffff9c RBP: 00007fb56e847c10 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd R13: 00007fb570027038 R14: 00007fb570026fa0 R15: 00007ffec4d67038 Modules linked in: ---[ end trace c5cb683666f83eef ]--- RIP: 0010:steam_send_report+0x66/0x310 drivers/hid/hid-steam.c:172 Code: 80 3c 18 00 74 12 4c 89 f7 e8 c6 34 3f fe 48 ba 00 00 00 00 00 fc ff df 4d 8b 26 49 8d 9c 24 98 10 00 00 48 89 d8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 df e8 9c 34 3f fe 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90000f77668 EFLAGS: 00010202 RAX: 0000000000000213 RBX: 0000000000001098 RCX: 0000000000000282 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff888123766030 RBP: ffffc90000f776b0 R08: dffffc0000000000 R09: fffff520001eeec9 R10: fffff520001eeec9 R11: 1ffff920001eeec8 R12: 0000000000000000 R13: 1ffff920001eeed8 R14: ffff888123766030 R15: ffffc90000f776e0 FS: 00007fb56e8486c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe03b73f98 CR3: 0000000124f02000 CR4: 00000000003506b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) 4: 74 12 je 0x18 6: 4c 89 f7 mov %r14,%rdi 9: e8 c6 34 3f fe call 0xfe3f34d4 e: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 15: fc ff df 18: 4d 8b 26 mov (%r14),%r12 1b: 49 8d 9c 24 98 10 00 lea 0x1098(%r12),%rbx 22: 00 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) <-- trapping instruction 2e: 74 12 je 0x42 30: 48 89 df mov %rbx,%rdi 33: e8 9c 34 3f fe call 0xfe3f34d4 38: 48 rex.W 39: ba 00 00 00 00 mov $0x0,%edx 3e: 00 fc add %bh,%ah