Re: [PATCH] i2c: ismt: Fix an out-of-bounds bug in ismt_access()

Wolfram Sang
2022-12-07T20:27:59Z

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On Fri, Jul 29, 2022 at 07:02:16PM +0800, Zheyu Ma wrote:
> 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: 13f35ac14cd0 ("i2c: Adding support for Intel iSMT SMBus 2.0 host controller")
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>

Applied to for-next, thanks!

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