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

Vulnerability 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.

References

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