WARNING in trace_event_raw_event_smbus_write

Status: upstream: reported C repro on 2026/08/11 09:19
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+2799d6178a1f91625aa4@syzkaller.appspotmail.com
First crash: 68d, last: 29d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/09/19 linux-6.1.y (ToT) 1a8763b93150 C [report] WARNING in trace_event_raw_event_smbus_write
2026/09/19 upstream (ToT) 40288c9206c1 C Didn't crash

Sample crash report:
------------[ cut here ]------------
memcpy: detected field-spanning write (size 35) of single field "entry->buf" at include/trace/events/smbus.h:60 (size 34)
WARNING: CPU: 1 PID: 4472 at include/trace/events/smbus.h:60 do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
WARNING: CPU: 1 PID: 4472 at include/trace/events/smbus.h:60 trace_event_raw_event_smbus_write+0x338/0x44c include/trace/events/smbus.h:23
Modules linked in:
CPU: 1 PID: 4472 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
pc : trace_event_raw_event_smbus_write+0x338/0x44c include/trace/events/smbus.h:23
lr : do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
lr : trace_event_raw_event_smbus_write+0x338/0x44c include/trace/events/smbus.h:23
sp : ffff8000212877c0
x29: ffff800021287880 x28: dfff800000000000 x27: ffff700004250efc
x26: ffff8000212877e0 x25: ffff0000d270d118 x24: 0000000000000000
x23: 0000000000000000 x22: ffff800021287b60 x21: 0000000000000023
x20: ffff0000c43223fc x19: ffff800017d7f000 x18: 0000000000000000
x17: 20646c6569662065 x16: ffff800011ba0e90 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033e721a3 x12: 0000000000000000
x11: ff00800008195f68 x10: 0000000000000000 x9 : 9b1fef44c796f600
x8 : 9b1fef44c796f600 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021287258 x4 : ffff800015484e80 x3 : ffff800008540dd8
x2 : 0000000000000001 x1 : 0000000100000002 x0 : 0000000000000000
Call trace:
 do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
 trace_event_raw_event_smbus_write+0x338/0x44c include/trace/events/smbus.h:23
 __traceiter_smbus_write include/trace/events/smbus.h:23 [inline]
 trace_smbus_write include/trace/events/smbus.h:23 [inline]
 __i2c_smbus_xfer+0x2110/0x23f0 drivers/i2c/i2c-core-smbus.c:571
 i2c_smbus_xfer+0x1f0/0x314 drivers/i2c/i2c-core-smbus.c:545
 i2cdev_ioctl_smbus+0x444/0x698 drivers/i2c/i2c-dev.c:381
 i2cdev_ioctl+0x744/0x984 drivers/i2c/i2c-dev.c:467
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x200/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 17122
hardirqs last  enabled at (17121): [<ffff8000083138a0>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (17122): [<ffff800011b9d0cc>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (17078): [<ffff800008031254>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (17076): [<ffff800008031220>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---
==================================================================
BUG: KASAN: stack-out-of-bounds in do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
BUG: KASAN: stack-out-of-bounds in trace_event_raw_event_smbus_write+0x294/0x44c include/trace/events/smbus.h:23
Read of size 35 at addr ffff800021287b60 by task syz.0.17/4472

CPU: 1 PID: 4472 Comm: syz.0.17 Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x258/0x290 mm/kasan/generic.c:189
 memcpy+0x48/0x90 mm/kasan/shadow.c:65
 do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
 trace_event_raw_event_smbus_write+0x294/0x44c include/trace/events/smbus.h:23
 __traceiter_smbus_write include/trace/events/smbus.h:23 [inline]
 trace_smbus_write include/trace/events/smbus.h:23 [inline]
 __i2c_smbus_xfer+0x2110/0x23f0 drivers/i2c/i2c-core-smbus.c:571
 i2c_smbus_xfer+0x1f0/0x314 drivers/i2c/i2c-core-smbus.c:545
 i2cdev_ioctl_smbus+0x444/0x698 drivers/i2c/i2c-dev.c:381
 i2cdev_ioctl+0x744/0x984 drivers/i2c/i2c-dev.c:467
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x200/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to stack of task syz.0.17/4472
 and is located at offset 32 in frame:
 i2cdev_ioctl_smbus+0x0/0x698 drivers/i2c/i2c-dev.c:309

This frame has 1 object:
 [32, 66) 'temp'

The buggy address belongs to a 8-page vmalloc region starting at 0xffff800021280000 allocated at copy_process+0x4ec/0x38b4 kernel/fork.c:2192
The buggy address belongs to the physical page:
page:000000009f6aafcb refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11e119
memcg:ffff0000cac9b302
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff0000cac9b302
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff800021287a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff800021287b00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
>ffff800021287b80: 02 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
                   ^
 ffff800021287c00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f8 f2 f8 f8
 ffff800021287c80: f2 f2 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00
==================================================================
i2c i2c-0: Invalid block write size 34

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/12 14:52 linux-6.1.y cf82dcca9634 70a60e12 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in trace_event_raw_event_smbus_write
2026/09/12 23:28 linux-6.1.y cf82dcca9634 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in trace_event_raw_event_smbus_write
2026/09/12 13:27 linux-6.1.y cf82dcca9634 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in trace_event_raw_event_smbus_write
2026/08/11 09:19 linux-6.1.y e4f7d8be268e 508909ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in trace_event_raw_event_smbus_write
* Struck through repros no longer work on HEAD.