R10: 0000000007fffffc R11: 0000000000000246 R12: 0000000000000002 R13: 00007fffedaf401f R14: 00007fa17636f300 R15: 0000000000022000 CPU: 1 PID: 14072 Comm: syz-executor.1 Not tainted 6.3.0-rc6-next-20230413 #1 general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN NOPTI Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] Call Trace: CPU: 0 PID: 14068 Comm: syz-executor.7 Not tainted 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 dump_stack_lvl+0xc1/0xf0 RIP: 0010:folio_wait_stable+0x23/0xe0 should_fail_ex+0x4b4/0x5b0 Code: 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 fd 53 e8 62 58 e7 ff 48 8d 7d 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a4 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b prepare_alloc_pages+0x178/0x500 RSP: 0018:ffff88800fb2f810 EFLAGS: 00010213 RAX: dffffc0000000000 RBX: ffff888047af1680 RCX: ffffc90007835000 __alloc_pages+0x149/0x480 RDX: 0000000000000001 RSI: ffffffff81646e3e RDI: 000000000000000c RBP: fffffffffffffff4 R08: 0000000000000001 R09: ffffffff856c1213 R10: fffffbfff0ad8242 R11: 0000000000000001 R12: 0000000000000000 R13: ffff888047af18a8 R14: 0000000000000000 R15: 0000000008000000 alloc_pages+0x1a0/0x260 FS: 00007fa17636f700(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000 filemap_alloc_folio+0x374/0x410 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e22d000 CR3: 000000003f788000 CR4: 0000000000350ef0 Call Trace: __filemap_get_folio+0x285/0x8d0 ext4_move_extents+0x12a7/0x34e0 ext4_da_write_begin+0x38d/0x830 generic_perform_write+0x25a/0x580 __ext4_ioctl+0x2ccc/0x4250 ext4_buffered_write_iter+0x164/0x460 ext4_file_write_iter+0x3ff/0x1950 do_iter_readv_writev+0x211/0x3c0 do_iter_write+0x189/0x7e0 vfs_writev+0x1ae/0x660 __x64_sys_ioctl+0x19e/0x210 __x64_sys_pwritev+0x233/0x310 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f62aab14b19 do_syscall_64+0x3f/0x90 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 bc ff ff ff f7 d8 64 89 01 48 entry_SYSCALL_64_after_hwframe+0x72/0xdc RSP: 002b:00007f62a808a188 EFLAGS: 00000246 RIP: 0033:0x7fa178df9b19 ORIG_RAX: 0000000000000010 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 bc ff ff ff f7 d8 64 89 01 48 RAX: ffffffffffffffda RBX: 00007f62aac27f60 RCX: 00007f62aab14b19 RSP: 002b:00007fa17636f188 EFLAGS: 00000246 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 ORIG_RAX: 0000000000000128 RBP: 00007f62a808a1d0 R08: 0000000000000000 R09: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fa178f0cf60 RCX: 00007fa178df9b19 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000007 R13: 00007ffc1811f2df R14: 00007f62a808a300 R15: 0000000000022000 RBP: 00007fa17636f1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000007fffffc R11: 0000000000000246 R12: 0000000000000002 R13: 00007fffedaf401f R14: 00007fa17636f300 R15: 0000000000022000 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:folio_wait_stable+0x23/0xe0 Code: 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 fd 53 e8 62 58 e7 ff 48 8d 7d 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a4 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b RSP: 0018:ffff88800fb2f810 EFLAGS: 00010213 RAX: dffffc0000000000 RBX: ffff888047af1680 RCX: ffffc90007835000 RDX: 0000000000000001 RSI: ffffffff81646e3e RDI: 000000000000000c RBP: fffffffffffffff4 R08: 0000000000000001 R09: ffffffff856c1213 R10: fffffbfff0ad8242 R11: 0000000000000001 R12: 0000000000000000 R13: ffff888047af18a8 R14: 0000000000000000 R15: 0000000008000000 FS: 00007fa17636f700(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e22d000 CR3: 000000003f788000 CR4: 0000000000350ef0 FAULT_INJECTION: forcing a failure. name fail_page_alloc, interval 1, probability 0, space 0, times 0 CPU: 1 PID: 14085 Comm: syz-executor.1 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 prepare_alloc_pages+0x178/0x500 __alloc_pages+0x149/0x480 alloc_pages+0x1a0/0x260 filemap_alloc_folio+0x374/0x410 __filemap_get_folio+0x285/0x8d0 ext4_move_extents+0x12a7/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f62aab14b19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f62a808a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f62aac27f60 RCX: 00007f62aab14b19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007f62a808a1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffc1811f2df R14: 00007f62a808a300 R15: 0000000000022000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 1 PID: 14096 Comm: syz-executor.4 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 should_failslab+0x9/0x20 __kmem_cache_alloc_node+0x5b/0x310 __kmalloc+0x4a/0x160 ext4_find_extent+0xa41/0xd30 ext4_swap_extents+0x362/0x1480 ext4_move_extents+0x16a5/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f7d10e5ab19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7d0e3d0188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f7d10f6df60 RCX: 00007f7d10e5ab19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007f7d0e3d01d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffd3a70a81f R14: 00007f7d0e3d0300 R15: 0000000000022000 CPU: 0 PID: 14091 Comm: syz-executor.6 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 should_failslab+0x9/0x20 kmem_cache_alloc+0x5a/0x390 jbd2__journal_start+0x194/0x810 __ext4_journal_start_sb+0x3d7/0x560 ext4_move_extents+0x1046/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f85af980b19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f85acef6188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f85afa93f60 RCX: 00007f85af980b19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007f85acef61d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffd9619d5ff R14: 00007f85acef6300 R15: 0000000000022000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 0 PID: 14100 Comm: syz-executor.5 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 should_failslab+0x9/0x20 __kmem_cache_alloc_node+0x5b/0x310 __kmalloc+0x4a/0x160 ext4_find_extent+0xa41/0xd30 ext4_swap_extents+0x362/0x1480 ext4_move_extents+0x16a5/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fccb6aeab19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fccb4060188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fccb6bfdf60 RCX: 00007fccb6aeab19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007fccb40601d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffcfcec47df R14: 00007fccb4060300 R15: 0000000000022000 FAULT_INJECTION: forcing a failure. name fail_page_alloc, interval 1, probability 0, space 0, times 0 CPU: 0 PID: 14109 Comm: syz-executor.4 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 prepare_alloc_pages+0x178/0x500 __alloc_pages+0x149/0x480 alloc_pages+0x1a0/0x260 filemap_alloc_folio+0x374/0x410 __filemap_get_folio+0x285/0x8d0 ext4_move_extents+0x1244/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f7d10e5ab19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7d0e3d0188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f7d10f6df60 RCX: 00007f7d10e5ab19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007f7d0e3d01d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffd3a70a81f R14: 00007f7d0e3d0300 R15: 0000000000022000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 0 PID: 14112 Comm: syz-executor.1 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 should_fail_ex+0x4b4/0x5b0 should_failslab+0x9/0x20 __kmem_cache_alloc_node+0x5b/0x310 __kmalloc+0x4a/0x160 ext4_find_extent+0xa41/0xd30 ext4_swap_extents+0x362/0x1480 ext4_move_extents+0x16a5/0x34e0 __ext4_ioctl+0x2ccc/0x4250 __x64_sys_ioctl+0x19e/0x210 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7f62aab14b19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f62a808a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f62aac27f60 RCX: 00007f62aab14b19 RDX: 0000000020000000 RSI: 00000000c028660f RDI: 0000000000000005 RBP: 00007f62a808a1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffc1811f2df R14: 00007f62a808a300 R15: 0000000000022000 ================================================================== BUG: KASAN: slab-use-after-free in rwsem_down_write_slowpath+0x13a6/0x14a0 Read of size 4 at addr ffff88800f425074 by task syz-executor.7/3856 CPU: 0 PID: 3856 Comm: syz-executor.7 Tainted: G D 6.3.0-rc6-next-20230413 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x91/0xf0 print_report+0xcc/0x620 kasan_report+0xc0/0xf0 rwsem_down_write_slowpath+0x13a6/0x14a0 down_write+0x1c3/0x1f0 vfs_unlink+0xd9/0x930 do_unlinkat+0x3b9/0x650 __x64_sys_unlink+0xca/0x110 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fa178df9457 Code: 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffedaf3168 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa178df9457 RDX: 00007fffedaf31a0 RSI: 00007fffedaf31a0 RDI: 00007fffedaf3230 RBP: 00007fffedaf3230 R08: 0000000000000001 R09: 00007fffedaf3000 R10: 00005555574bed13 R11: 0000000000000206 R12: 00007fa178e53105 R13: 00007fffedaf42f0 R14: 00005555574bec20 R15: 00007fffedaf4330 Allocated by task 14067: kasan_save_stack+0x22/0x50 kasan_set_track+0x25/0x30 __kasan_slab_alloc+0x59/0x70 kmem_cache_alloc_node+0x189/0x3a0 copy_process+0x3c2/0x7330 kernel_clone+0xeb/0x7d0 __do_sys_clone+0xba/0x100 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc Freed by task 14067: kasan_save_stack+0x22/0x50 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2e/0x50 __kasan_slab_free+0x10a/0x190 kmem_cache_free+0xff/0x4a0 _free_event+0xab4/0x1150 perf_event_release_kernel+0x5b8/0x7a0 perf_release+0x37/0x50 __fput+0x263/0xa40 task_work_run+0x174/0x280 exit_to_user_mode_prepare+0x17d/0x180 syscall_exit_to_user_mode+0x1d/0x50 do_syscall_64+0x4c/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc Last potentially related work creation: kasan_save_stack+0x22/0x50 __kasan_record_aux_stack+0x95/0xb0 __call_rcu_common.constprop.0+0x6a/0xb90 put_task_struct_rcu_user+0x87/0xd0 __schedule+0x995/0x2a00 schedule+0xdb/0x1a0 do_nanosleep+0x154/0x510 hrtimer_nanosleep+0x208/0x590 common_nsleep+0xaa/0xd0 __x64_sys_clock_nanosleep+0x335/0x480 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc Second to last potentially related work creation: kasan_save_stack+0x22/0x50 __kasan_record_aux_stack+0x95/0xb0 __call_rcu_common.constprop.0+0x6a/0xb90 put_task_struct_rcu_user+0x87/0xd0 __schedule+0x995/0x2a00 __cond_resched+0x46/0x70 dput+0x54/0xe60 step_into+0x1084/0x2000 walk_component+0xf5/0x5b0 link_path_walk.part.0+0x76e/0xd90 path_openat+0x24e/0x2750 do_filp_open+0x1ba/0x410 do_sys_openat2+0x171/0x4c0 __x64_sys_openat+0x143/0x200 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc The buggy address belongs to the object at ffff88800f425040 which belongs to the cache task_struct of size 6592 The buggy address is located 52 bytes inside of freed 6592-byte region [ffff88800f425040, ffff88800f426a00) The buggy address belongs to the physical page: page:00000000a1cdf78d refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xf420 head:00000000a1cdf78d order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff888006bc5341 flags: 0x100000000010200(slab|head|node=0|zone=1) page_type: 0xffffffff() raw: 0100000000010200 ffff888008792640 ffffea000119c000 dead000000000002 raw: 0000000000000000 0000000000040004 00000001ffffffff ffff888006bc5341 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88800f424f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88800f424f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88800f425000: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ^ ffff88800f425080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88800f425100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 90 nop 1: 90 nop 2: 90 nop 3: 90 nop 4: 90 nop 5: 90 nop 6: 90 nop 7: f3 0f 1e fa endbr64 b: 55 push %rbp c: 48 89 fd mov %rdi,%rbp f: 53 push %rbx 10: e8 62 58 e7 ff callq 0xffe75877 15: 48 8d 7d 18 lea 0x18(%rbp),%rdi 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 0f 85 a4 00 00 00 jne 0xd8 34: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 3b: fc ff df 3e: 48 rex.W 3f: 8b .byte 0x8b