[v6.1] WARNING in trace_event_raw_event_smbus_write

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=132a9879580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=2799d6178a1f91625aa4
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7cd9b1875376/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b5d35d18c31/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d5ee64c2af77/Image-e4f7d8be.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2799d6...@syzkaller.appspotmail.com

------------[ 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: 0 PID: 7633 at include/trace/events/smbus.h:60 do_trace_event_raw_event_smbus_write include/trace/events/smbus.h:60 [inline]
WARNING: CPU: 0 PID: 7633 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: 0 PID: 7633 Comm: syz.8.658 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
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 : ffff8000211e77c0
x29: ffff8000211e7880 x28: dfff800000000000 x27: ffff70000423cefc
x26: ffff8000211e77e0 x25: ffff0000cbe85118 x24: 0000000000000000
x23: 0000000000000000 x22: ffff8000211e7b60 x21: 0000000000000023
x20: ffff0000c0031a14 x19: ffff800017d5e000 x18: 0000000000000000
x17: 20646c6569662065 x16: ffff8000082dd248 x15: 0000000000000002
x14: 0000000000000001 x13: 1ffff0000423ce48 x12: 0000000000080000
x11: 0000000000006e06 x10: ffff800033f4f000 x9 : 862bb9f6abf09c00
x8 : 862bb9f6abf09c00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000211e7258 x4 : ffff800015464e80 x3 : ffff80000831d354
x2 : 0000000000000001 x1 : 0000000000000002 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: 1250
hardirqs last enabled at (1249): [<ffff80000831388c>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (1250): [<ffff800011b8c2bc>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last enabled at (1244): [<ffff8000081ae3bc>] softirq_handle_end kernel/softirq.c:439 [inline]
softirqs last enabled at (1244): [<ffff8000081ae3bc>] handle_softirqs+0xb1c/0xc90 kernel/softirq.c:624
softirqs last disabled at (1235): [<ffff800008020e6c>] __do_softirq+0x14/0x20 kernel/softirq.c:630
---[ 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 ffff8000211e7b60 by task syz.8.658/7633

CPU: 0 PID: 7633 Comm: syz.8.658 Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
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.8.658/7633
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 0xffff8000211e0000 allocated at copy_process+0x4ec/0x38f4 kernel/fork.c:2188
The buggy address belongs to the physical page:
page:000000006c941d0d refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b350
memcg:ffff0000db5f7702
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff0000db5f7702
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8000211e7a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8000211e7b00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
>ffff8000211e7b80: 02 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
^
ffff8000211e7c00: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f8 f2 f8 f8
ffff8000211e7c80: f2 f2 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00
==================================================================
i2c i2c-0: Invalid block write size 34


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