Extracting prog: 2m21.322316445s
Minimizing prog: 6m12.42192581s
Simplifying prog options: 8m41.520817125s
Extracting C: 34.580984806s
Simplifying C: 0s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
single: successfully extracted reproducer
found reproducer with 2 syscalls
minimizing guilty program
testing program (duration=47.55197118s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf
detailed listing:
executing program 0:
openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)

program did not crash
testing program (duration=47.55197118s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
ioctl$UDMABUF_CREATE(0xffffffffffffffff, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program did not crash
testing program (duration=47.55197118s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, 0x0, 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program did not crash
testing program (duration=47.55197118s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=47.55197118s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
program did not crash
simplifying guilty program options
testing program (duration=47.55197118s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
extracting C reproducer
testing compiled C program (duration=47.55197118s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
program did not crash
testing program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
extracting C reproducer
testing compiled C program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:namespace SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
program did not crash
testing program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
extracting C reproducer
testing compiled C program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
program did not crash
testing program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
validation run: crashed=true
testing program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
validation run: crashed=true
testing program (duration=47.55197118s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$udambuf-ioctl$UDMABUF_CREATE
detailed listing:
executing program 0:
r0 = openat$udambuf(0xffffffffffffff9c, &(0x7f0000001300), 0x2)
ioctl$UDMABUF_CREATE(r0, 0x40187542, &(0x7f0000001680)={0xffffffffffffffff, 0x0, 0x0, 0x1000000000000})

program crashed: WARNING in udmabuf_create
validation run: crashed=true
reproducing took 23m13.975396353s
repro crashed as (corrupted=false):
------------[ cut here ]------------
!(flags & __GFP_NOWARN)
WARNING: mm/slub.c:6908 at __kvmalloc_node_noprof+0x7de/0x870 mm/slub.c:6908, CPU#0: syz.0.17/5863
Modules linked in:
CPU: 0 UID: 0 PID: 5863 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__kvmalloc_node_noprof+0x7de/0x870 mm/slub.c:6908
Code: ff 48 c7 c7 b0 3b e9 8e 48 89 de e8 5c cf ed 02 e9 fd fb ff ff 48 c7 c7 f0 3b e9 8e 48 89 de e8 48 cf ed 02 e9 32 fc ff ff 90 <0f> 0b 90 45 31 f6 e9 ef fd ff ff 90 0f 0b 90 e9 46 ff ff ff 49 83
RSP: 0018:ffffc900038ef938 EFLAGS: 00010246
RAX: 0000000000000100 RBX: 00000000000028c0 RCX: 8000000000000001
RDX: 0000008000000000 RSI: ffffffff8c6d5760 RDI: ffffffff8c6d5720
RBP: 0000008000000000 R08: 00000000000028c0 R09: 00000000ffffffff
R10: 0000000000000006 R11: 0000000000000000 R12: 00000000ffffffff
R13: ffffffff8653ddcc R14: 0000000000000000 R15: 0000008000000000
FS:  0000000000000000(0000) GS:ffff888124cf3000(0063) knlGS:0000000057b56480
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f7163140 CR3: 00000000721a0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 init_udmabuf drivers/dma-buf/udmabuf.c:193 [inline]
 udmabuf_create+0x2dc/0xf50 drivers/dma-buf/udmabuf.c:386
 udmabuf_ioctl_create drivers/dma-buf/udmabuf.c:465 [inline]
 udmabuf_ioctl+0x1f3/0x300 drivers/dma-buf/udmabuf.c:496
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x27a/0x6a0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf701f0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000fff8024c EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000040187542
RDX: 0000000080001680 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	85 d2                	test   %edx,%edx
   3:	74 0a                	je     0xf
   5:	89 ce                	mov    %ecx,%esi
   7:	81 e6 ff 0f 00 00    	and    $0xfff,%esi
   d:	89 32                	mov    %esi,(%rdx)
   f:	85 c0                	test   %eax,%eax
  11:	74 05                	je     0x18
  13:	c1 e9 0c             	shr    $0xc,%ecx
  16:	89 08                	mov    %ecx,(%rax)
  18:	31 c0                	xor    %eax,%eax
  1a:	5e                   	pop    %rsi
  1b:	5d                   	pop    %rbp
  1c:	c3                   	ret
  1d:	90                   	nop
  1e:	0f 1f 00             	nopl   (%rax)
  21:	51                   	push   %rcx
  22:	52                   	push   %rdx
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	ret
  2e:	90                   	nop
  2f:	90                   	nop
  30:	90                   	nop
  31:	90                   	nop
  32:	90                   	nop
  33:	90                   	nop
  34:	90                   	nop
  35:	90                   	nop
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	58                   	pop    %rax
  3f:	b8                   	.byte 0xb8

final repro crashed as (corrupted=false):
------------[ cut here ]------------
!(flags & __GFP_NOWARN)
WARNING: mm/slub.c:6908 at __kvmalloc_node_noprof+0x7de/0x870 mm/slub.c:6908, CPU#0: syz.0.17/5863
Modules linked in:
CPU: 0 UID: 0 PID: 5863 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__kvmalloc_node_noprof+0x7de/0x870 mm/slub.c:6908
Code: ff 48 c7 c7 b0 3b e9 8e 48 89 de e8 5c cf ed 02 e9 fd fb ff ff 48 c7 c7 f0 3b e9 8e 48 89 de e8 48 cf ed 02 e9 32 fc ff ff 90 <0f> 0b 90 45 31 f6 e9 ef fd ff ff 90 0f 0b 90 e9 46 ff ff ff 49 83
RSP: 0018:ffffc900038ef938 EFLAGS: 00010246
RAX: 0000000000000100 RBX: 00000000000028c0 RCX: 8000000000000001
RDX: 0000008000000000 RSI: ffffffff8c6d5760 RDI: ffffffff8c6d5720
RBP: 0000008000000000 R08: 00000000000028c0 R09: 00000000ffffffff
R10: 0000000000000006 R11: 0000000000000000 R12: 00000000ffffffff
R13: ffffffff8653ddcc R14: 0000000000000000 R15: 0000008000000000
FS:  0000000000000000(0000) GS:ffff888124cf3000(0063) knlGS:0000000057b56480
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f7163140 CR3: 00000000721a0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 init_udmabuf drivers/dma-buf/udmabuf.c:193 [inline]
 udmabuf_create+0x2dc/0xf50 drivers/dma-buf/udmabuf.c:386
 udmabuf_ioctl_create drivers/dma-buf/udmabuf.c:465 [inline]
 udmabuf_ioctl+0x1f3/0x300 drivers/dma-buf/udmabuf.c:496
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x27a/0x6a0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf701f0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000fff8024c EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000040187542
RDX: 0000000080001680 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	85 d2                	test   %edx,%edx
   3:	74 0a                	je     0xf
   5:	89 ce                	mov    %ecx,%esi
   7:	81 e6 ff 0f 00 00    	and    $0xfff,%esi
   d:	89 32                	mov    %esi,(%rdx)
   f:	85 c0                	test   %eax,%eax
  11:	74 05                	je     0x18
  13:	c1 e9 0c             	shr    $0xc,%ecx
  16:	89 08                	mov    %ecx,(%rax)
  18:	31 c0                	xor    %eax,%eax
  1a:	5e                   	pop    %rsi
  1b:	5d                   	pop    %rbp
  1c:	c3                   	ret
  1d:	90                   	nop
  1e:	0f 1f 00             	nopl   (%rax)
  21:	51                   	push   %rcx
  22:	52                   	push   %rdx
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	ret
  2e:	90                   	nop
  2f:	90                   	nop
  30:	90                   	nop
  31:	90                   	nop
  32:	90                   	nop
  33:	90                   	nop
  34:	90                   	nop
  35:	90                   	nop
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	58                   	pop    %rax
  3f:	b8                   	.byte 0xb8