i2c: ismt: Fix an out-of-bounds bug in ismt_access()

stable inclusion
from stable-v5.15.86
commit 96c12fd0ec74641295e1c3c34dea3dce1b6c3422
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5MZPE
CVE: CVE-2022-2873

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.15.86&id=96c12fd0ec74641295e1c3c34dea3dce1b6c3422



--------------------------------

[ Upstream commit 39244cc7 ]

When the driver does not check the data from the user, the variable
'data->block[0]' may be very large to cause an out-of-bounds bug.

The following log can reveal it:

[   33.995542] i2c i2c-1: ioctl, cmd=0x720, arg=0x7ffcb3dc3a20
[   33.995978] ismt_smbus 0000:00:05.0: I2C_SMBUS_BLOCK_DATA:  WRITE
[   33.996475] ==================================================================
[   33.996995] BUG: KASAN: out-of-bounds in ismt_access.cold+0x374/0x214b
[   33.997473] Read of size 18446744073709551615 at addr ffff88810efcfdb1 by task ismt_poc/485
[   33.999450] Call Trace:
[   34.001849]  memcpy+0x20/0x60
[   34.002077]  ismt_access.cold+0x374/0x214b
[   34.003382]  __i2c_smbus_xfer+0x44f/0xfb0
[   34.004007]  i2c_smbus_xfer+0x10a/0x390
[   34.004291]  i2cdev_ioctl_smbus+0x2c8/0x710
[   34.005196]  i2cdev_ioctl+0x5ec/0x74c

Fix this bug by checking the size of 'data->block[0]' first.

Fixes: 13f35ac1 ("i2c: Adding support for Intel iSMT SMBus 2.0 host controller")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
(cherry picked from commit 9da915fa)