syzbot
KASAN: use-after-free Read in check_tty_count
Status:
upstream: reported C repro on 2026/08/10 10:56
Bug presence:
origin:upstream
[Documentation on labels]
Reported-by: syzbot+eb4da01ac4602c751ae0@syzkaller.appspotmail.com
First crash: 65d, last: 24d
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Bug presence (2)
| Date |
Name |
Commit |
Repro |
Result |
| 2026/08/21 |
lts (merge base) |
228da13e907e |
C
|
[report] KASAN: use-after-free Read in check_tty_count
|
| 2026/08/21 |
upstream (ToT) |
818bebeb63dd |
C
|
[report] KASAN: slab-use-after-free Read in check_tty_count
|
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▼
Last patch testing requests (3)
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▼
Fix bisection attempts (1)
Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: use-after-free in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: use-after-free in tty_port_kopened include/linux/tty_port.h:228 [inline]
BUG: KASAN: use-after-free in check_tty_count+0x1a8/0x330 drivers/tty/tty_io.c:287
Read of size 8 at addr ffff88810e764110 by task syz-executor327/316
CPU: 1 PID: 316 Comm: syz-executor327 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_address_description+0x71/0x200 mm/kasan/report.c:316
print_report+0x4a/0x60 mm/kasan/report.c:420
kasan_report+0x122/0x150 mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
__kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
instrument_atomic_read include/linux/instrumented.h:72 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
tty_port_kopened include/linux/tty_port.h:228 [inline]
check_tty_count+0x1a8/0x330 drivers/tty/tty_io.c:287
tty_release+0x88/0x11d0 drivers/tty/tty_io.c:1736
__fput+0x1fd/0x8f0 fs/file_table.c:320
____fput+0x15/0x20 fs/file_table.c:348
task_work_run+0x1e1/0x250 kernel/task_work.c:203
ptrace_notify+0x23f/0x270 kernel/signal.c:2388
ptrace_report_syscall include/linux/ptrace.h:424 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:486 [inline]
syscall_exit_work+0x84/0x140 kernel/entry/common.c:258
syscall_exit_to_user_mode_prepare+0x1c/0x20 kernel/entry/common.c:285
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0xd/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa2d8359b8e
Code: 08 0f 85 65 e1 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007ffcb0d63a98 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055558e12c3c0 RCX: 00007fa2d8359b8e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000006917 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa2d83f5b2c
R13: 00007ffcb0d63b40 R14: 00007ffcb0d63bb0 R15: 00007fa2d832e6d0
</TASK>
Allocated by task 317:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
____kasan_kmalloc mm/kasan/common.c:380 [inline]
__kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
kasan_kmalloc include/linux/kasan.h:212 [inline]
kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
gs_port_alloc drivers/usb/gadget/function/u_serial.c:1166 [inline]
gserial_alloc_line_no_console+0x238/0x700 drivers/usb/gadget/function/u_serial.c:1246
gserial_alloc_line+0x15/0x20 drivers/usb/gadget/function/u_serial.c:1280
acm_alloc_instance+0x86/0xe0 drivers/usb/gadget/function/f_acm.c:845
try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
usb_get_function_instance+0xf3/0x310 drivers/usb/gadget/functions.c:44
function_make+0x118/0x360 drivers/usb/gadget/configfs.c:652
configfs_mkdir+0x518/0x9e0 fs/configfs/dir.c:1329
vfs_mkdir+0x39c/0x580 fs/namei.c:4113
do_mkdirat+0x174/0x4d0 fs/namei.c:4138
__do_sys_mkdirat fs/namei.c:4153 [inline]
__se_sys_mkdirat fs/namei.c:4151 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151
x64_sys_call+0x73d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 317:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
kasan_slab_free include/linux/kasan.h:178 [inline]
slab_free_hook mm/slub.c:1750 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
slab_free mm/slub.c:3712 [inline]
__kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
kfree+0x6f/0xf0 mm/slab_common.c:990
gserial_free_port+0x240/0x2d0 drivers/usb/gadget/function/u_serial.c:1210
gserial_free_line+0x9b/0x1a0 drivers/usb/gadget/function/u_serial.c:1227
acm_free_instance+0x39/0x60 drivers/usb/gadget/function/f_acm.c:832
usb_put_function_instance+0x9b/0xc0 drivers/usb/gadget/functions.c:77
acm_attr_release+0x15/0x20 drivers/usb/gadget/function/f_acm.c:781
config_item_cleanup fs/configfs/item.c:128 [inline]
config_item_release fs/configfs/item.c:137 [inline]
kref_put include/linux/kref.h:65 [inline]
config_item_put+0x166/0x210 fs/configfs/item.c:149
configfs_rmdir+0x8c9/0x980 fs/configfs/dir.c:1540
vfs_rmdir+0x381/0x4f0 fs/namei.c:4198
do_rmdir+0x261/0x6b0 fs/namei.c:4259
__do_sys_rmdir fs/namei.c:4278 [inline]
__se_sys_rmdir fs/namei.c:4276 [inline]
__x64_sys_rmdir+0x49/0x50 fs/namei.c:4276
x64_sys_call+0x68e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:85
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff88810e764000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 272 bytes inside of
1024-byte region [ffff88810e764000, ffff88810e764400)
The buggy address belongs to the physical page:
page:ffffea000439d800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10e760
head:ffffea000439d800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100043080
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 313, tgid 313 (syz-executor327), ts 26837077746, free_ts 18965421948
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2673
prep_new_page+0x1c/0x110 mm/page_alloc.c:2680
get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4587
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5931
alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
allocate_slab mm/slub.c:1967 [inline]
new_slab+0x98/0x3e0 mm/slub.c:2020
___slab_alloc+0x70f/0xb70 mm/slub.c:3177
__slab_alloc+0x5e/0xa0 mm/slub.c:3263
slab_alloc_node mm/slub.c:3348 [inline]
__kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
__do_kmalloc_node mm/slab_common.c:937 [inline]
__kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
kmalloc_reserve net/core/skbuff.c:449 [inline]
__alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
alloc_skb include/linux/skbuff.h:1322 [inline]
alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290
uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline]
kobject_uevent_net_broadcast+0x1b4/0x5b0 lib/kobject_uevent.c:412
kobject_uevent_env+0x541/0x720 lib/kobject_uevent.c:608
kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
device_add+0xa1a/0xec0 drivers/base/core.c:3679
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1581 [inline]
free_pcp_prepare mm/page_alloc.c:1655 [inline]
free_unref_page_prepare+0x81b/0x820 mm/page_alloc.c:3622
free_unref_page+0x93/0x530 mm/page_alloc.c:3720
free_the_page mm/page_alloc.c:863 [inline]
__free_pages+0x67/0x100 mm/page_alloc.c:6021
__free_slab+0xc7/0x1a0 mm/slub.c:2044
free_slab mm/slub.c:2059 [inline]
discard_slab mm/slub.c:2065 [inline]
__unfreeze_partials+0x15a/0x190 mm/slub.c:2614
put_cpu_partial+0xa9/0x100 mm/slub.c:2690
__slab_free+0x1c4/0x280 mm/slub.c:3589
do_slab_free mm/slub.c:3666 [inline]
___cache_free+0xbf/0xd0 mm/slub.c:3722
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0xc6/0x140 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:311
kasan_slab_alloc include/linux/kasan.h:202 [inline]
slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
slab_alloc_node mm/slub.c:3382 [inline]
slab_alloc mm/slub.c:3392 [inline]
__kmem_cache_alloc_lru mm/slub.c:3399 [inline]
kmem_cache_alloc+0x166/0x320 mm/slub.c:3408
mt_alloc_one lib/maple_tree.c:157 [inline]
mas_alloc_nodes+0x2d8/0x850 lib/maple_tree.c:1284
mas_node_count_gfp lib/maple_tree.c:1366 [inline]
mas_preallocate+0xe3d/0x1430 lib/maple_tree.c:5664
vma_expand+0x437/0xad0 mm/mmap.c:565
Memory state around the buggy address:
ffff88810e764000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810e764080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810e764100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88810e764180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810e764200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 316 at drivers/usb/gadget/function/u_serial.c:694 gs_close+0x17d/0x9b0 drivers/usb/gadget/function/u_serial.c:694
Modules linked in:
CPU: 0 PID: 316 Comm: syz-executor327 Tainted: G B syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:gs_close+0x17d/0x9b0 drivers/usb/gadget/function/u_serial.c:694
Code: 04 23 fe 41 ff cc 42 0f b6 04 2b 84 c0 0f 85 cf 06 00 00 48 8b 44 24 20 44 89 20 48 8b 5c 24 38 e9 cb 02 00 00 e8 f3 03 23 fe <0f> 0b 48 8b 5c 24 38 e9 ba 02 00 00 e8 e2 03 23 fe 49 8d bf a8 02
RSP: 0018:ffffc90000e67a60 EFLAGS: 00010093
RAX: ffffffff834e662d RBX: 1ffff11021cec81a RCX: ffff888110060000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000e67b80 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001ccf3c R12: 0000000000000000
R13: dffffc0000000000 R14: 1ffff920001ccf54 R15: ffff88810e764000
FS: 000055558e12c3c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558e135758 CR3: 0000000125fb9000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tty_release+0x32b/0x11d0 drivers/tty/tty_io.c:1753
__fput+0x1fd/0x8f0 fs/file_table.c:320
____fput+0x15/0x20 fs/file_table.c:348
task_work_run+0x1e1/0x250 kernel/task_work.c:203
ptrace_notify+0x23f/0x270 kernel/signal.c:2388
ptrace_report_syscall include/linux/ptrace.h:424 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:486 [inline]
syscall_exit_work+0x84/0x140 kernel/entry/common.c:258
syscall_exit_to_user_mode_prepare+0x1c/0x20 kernel/entry/common.c:285
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0xd/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa2d8359b8e
Code: 08 0f 85 65 e1 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007ffcb0d63a98 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055558e12c3c0 RCX: 00007fa2d8359b8e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000006917 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa2d83f5b2c
R13: 00007ffcb0d63b40 R14: 00007ffcb0d63bb0 R15: 00007fa2d832e6d0
</TASK>
---[ end trace 0000000000000000 ]---
general protection fault, probably for non-canonical address 0xe0b8dc25c0000020: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0x05c7012e00000100-0x05c7012e00000107]
CPU: 0 PID: 316 Comm: syz-executor327 Tainted: G B W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:get_work_pool kernel/workqueue.c:746 [inline]
RIP: 0010:try_to_grab_pending+0x1be/0x580 kernel/workqueue.c:1298
Code: 00 e8 b6 43 29 00 e9 0a 01 00 00 e8 ac 43 29 00 31 c0 e9 98 01 00 00 e8 a0 43 29 00 49 81 e6 00 ff ff ff 4c 89 f0 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 f7 e8 c4 ce 6e 00 49 8b 06 48 85 c0 0f 84
RSP: 0018:ffffc90000e67900 EFLAGS: 00010002
RAX: 00b8e025c0000020 RBX: dffffc0000000000 RCX: ffff888110060000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000000
RBP: ffffc90000e679b0 R08: 0000000000000007 R09: 00000000fffffffb
R10: dffffc0000000000 R11: ffffed1021cec801 R12: ffff88810e764008
R13: ffffc90000e679d8 R14: 05c7012e00000100 R15: 1ffff920001ccf3b
FS: 000055558e12c3c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558e135758 CR3: 0000000125fb9000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__cancel_work_timer+0xb5/0x4d0 kernel/workqueue.c:3132
cancel_work_sync+0x17/0x20 kernel/workqueue.c:3209
tty_buffer_cancel_work+0x19/0x20 drivers/tty/tty_buffer.c:692
release_tty+0x487/0x830 drivers/tty/tty_io.c:1596
tty_release_struct+0xbf/0xe0 drivers/tty/tty_io.c:1700
tty_release+0xbb7/0x11d0 drivers/tty/tty_io.c:1860
__fput+0x1fd/0x8f0 fs/file_table.c:320
____fput+0x15/0x20 fs/file_table.c:348
task_work_run+0x1e1/0x250 kernel/task_work.c:203
ptrace_notify+0x23f/0x270 kernel/signal.c:2388
ptrace_report_syscall include/linux/ptrace.h:424 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:486 [inline]
syscall_exit_work+0x84/0x140 kernel/entry/common.c:258
syscall_exit_to_user_mode_prepare+0x1c/0x20 kernel/entry/common.c:285
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0xd/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa2d8359b8e
Code: 08 0f 85 65 e1 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007ffcb0d63a98 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000055558e12c3c0 RCX: 00007fa2d8359b8e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000006917 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa2d83f5b2c
R13: 00007ffcb0d63b40 R14: 00007ffcb0d63bb0 R15: 00007fa2d832e6d0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:get_work_pool kernel/workqueue.c:746 [inline]
RIP: 0010:try_to_grab_pending+0x1be/0x580 kernel/workqueue.c:1298
Code: 00 e8 b6 43 29 00 e9 0a 01 00 00 e8 ac 43 29 00 31 c0 e9 98 01 00 00 e8 a0 43 29 00 49 81 e6 00 ff ff ff 4c 89 f0 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 f7 e8 c4 ce 6e 00 49 8b 06 48 85 c0 0f 84
RSP: 0018:ffffc90000e67900 EFLAGS: 00010002
RAX: 00b8e025c0000020 RBX: dffffc0000000000 RCX: ffff888110060000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000000
RBP: ffffc90000e679b0 R08: 0000000000000007 R09: 00000000fffffffb
R10: dffffc0000000000 R11: ffffed1021cec801 R12: ffff88810e764008
R13: ffffc90000e679d8 R14: 05c7012e00000100 R15: 1ffff920001ccf3b
FS: 000055558e12c3c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558e135758 CR3: 0000000125fb9000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 e8 add %ch,%al
2: b6 43 mov $0x43,%dh
4: 29 00 sub %eax,(%rax)
6: e9 0a 01 00 00 jmp 0x115
b: e8 ac 43 29 00 call 0x2943bc
10: 31 c0 xor %eax,%eax
12: e9 98 01 00 00 jmp 0x1af
17: e8 a0 43 29 00 call 0x2943bc
1c: 49 81 e6 00 ff ff ff and $0xffffffffffffff00,%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 f7 mov %r14,%rdi
33: e8 c4 ce 6e 00 call 0x6ecefc
38: 49 8b 06 mov (%r14),%rax
3b: 48 85 c0 test %rax,%rax
3e: 0f .byte 0xf
3f: 84 .byte 0x84
Struck through repros no longer work on HEAD.