Re: [PATCH] i2c: dev: Fix field-spanning write in __do_trace_smbus_write()

[Wang Liang <wangliang74@huawei.com>]

在 2025/9/18 19:39, Wang Liang 写道:
> A field-spanning write warning was observed with following output:
>
>    ------------[ cut here ]------------
>    memcpy: detected field-spanning write (size 86) of single field "entry->buf" at ./include/trace/events/smbus.h:60 (size 34)
>    WARNING: CPU: 1 PID: 2646 at ./include/trace/events/smbus.h:60
>    CPU: 1 UID: 0 PID: 2646 Comm: syz.0.310 Not tainted 6.17.0-rc5+ #5 PREEMPT(none)
>    RIP: 0010:do_trace_event_raw_event_smbus_write.constprop.0+0x37a/0x520 include/trace/events/smbus.h:23
>    Call Trace:
>     <TASK>
>     __do_trace_smbus_write include/trace/events/smbus.h:23 [inline]
>     trace_smbus_write include/trace/events/smbus.h:23 [inline]
>     __i2c_smbus_xfer.part.0+0x5ce/0x9a0 drivers/i2c/i2c-core-smbus.c:572
>     __i2c_smbus_xfer+0xa3/0x1a0 drivers/i2c/i2c-core-smbus.c:566
>     i2c_smbus_xfer drivers/i2c/i2c-core-smbus.c:546 [inline]
>     i2c_smbus_xfer+0x208/0x3c0 drivers/i2c/i2c-core-smbus.c:536
>     i2cdev_ioctl_smbus+0x2cd/0x850 drivers/i2c/i2c-dev.c:389
>     i2cdev_ioctl+0x3bb/0x800 drivers/i2c/i2c-dev.c:478
>     vfs_ioctl fs/ioctl.c:51 [inline]
>     __do_sys_ioctl fs/ioctl.c:598 [inline]
>     __se_sys_ioctl fs/ioctl.c:584 [inline]
>     __x64_sys_ioctl+0x191/0x210 fs/ioctl.c:584
>     do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>     do_syscall_64+0x5d/0x2d0 arch/x86/entry/syscall_64.c:94
>     entry_SYSCALL_64_after_hwframe+0x76/0x7e
>     </TASK>
>
> Similar to previous commit 57f312b95593 ("i2c: rtl9300: Fix out-of-bounds
> bug in rtl9300_i2c_smbus_xfer"), the data->block[0] is used for length and
> it comes from user. Add check for the variable to avoid out-of-bounds bug.
>
> Fixes: 8a325997d95d ("i2c: Add message transfer tracepoints for SMBUS [ver #2]")
> Signed-off-by: Wang Liang <wangliang74@huawei.com>
> ---
>   drivers/i2c/i2c-dev.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
> index e9577f920286..b00961561134 100644
> --- a/drivers/i2c/i2c-dev.c
> +++ b/drivers/i2c/i2c-dev.c
> @@ -386,6 +386,12 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
>   		if (read_write == I2C_SMBUS_READ)
>   			temp.block[0] = I2C_SMBUS_BLOCK_MAX;
>   	}
> +
> +	if (temp.block[0] > I2C_SMBUS_BLOCK_MAX) {
> +		dev_dbg(&client->adapter->dev, "block[0] out of range in ioctl I2C_SMBUS.\n");
> +		return -EINVAL;
> +	}
> +
>   	res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
>   	      read_write, command, size, &temp);
>   	if (!res && ((size == I2C_SMBUS_PROC_CALL) ||


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