CVE-2022-49551 Information

Description

In the Linux kernel the following vulnerability has been resolved:

usb: isp1760: Fix out-of-bounds array access

Running the driver through kasan gives an interesting splat:

BUG: KASAN: global-out-of-bounds in isp1760_register+0x180/0x70c Read of size 20 at addr f1db2e64 by task swapper/0/1 (…) isp1760_register from isp1760_plat_probe+0x1d8/0x220 (…)

This happens because the loop reading the regmap fields for the different ISP1760 variants look like this:

for (i = 0; i < HC_FIELD_MAX; i++) …

Meaning it expects the arrays to be at least HC_FIELD_MAX - 1 long.

However the arrays isp1760_hc_reg_fields[] isp1763_hc_reg_fields[] isp1763_hc_volatile_ranges[] and isp1763_dc_volatile_ranges[] are dynamically sized during compilation.

Fix this by putting an empty assignment to the [HC_FIELD_MAX] and [DC_FIELD_MAX] array member at the end of each array. This will make the array one member longer than it needs to be but avoids the risk of overwriting whatever is inside [HC_FIELD_MAX - 1] and is simple and intuitive to read. Also add comments explaining what is going on.

Reference

https://git.kernel.org/stable/c/26ae2c942b5702f2e43d36b2a4389cfb7d616b6a https://git.kernel.org/stable/c/463bddd3ff1acf4036ddb80c34a715eb99debf46 https://git.kernel.org/stable/c/47d39cb57e8669e507d17d9e0d067d2b3e3a87ae https://git.kernel.org/stable/c/bf2558bbdce3ab1d6bcba09f354914e4515d0a2b