In the Linux kernel, the following vulnerability has been resolved: cpufreq: imx6q: fix out-of-bounds write when probed more than once imx6_soc_volt is allocated fresh on every probe, sized to the number of ARM OPPs: imx6_soc_volt = …

Overview

In the Linux kernel, the following vulnerability has been resolved:

cpufreq: imx6q: fix out-of-bounds write when probed more than once

imx6_soc_volt is allocated fresh on every probe, sized to the number of ARM OPPs:

imx6_soc_volt = devm_kcalloc(cpu_dev, num, sizeof(*imx6_soc_volt),
			     GFP_KERNEL);

but it is filled through soc_opp_count, which has static storage and is never reset. A second bind after an unbind keeps indexing from where the first one stopped, and writes past the end of the new array.

Unbinding and rebinding the driver on qemu's mcimx6ul-evk, under KASAN:

BUG: KASAN: slab-out-of-bounds in imx6q_cpufreq_probe+0x3b0/0xa34 Write of size 4 at addr c5e90480 by task binder/73 imx6q_cpufreq_probe from platform_probe+0x88/0xe4 platform_probe from really_probe+0x108/0x384 bind_store from kernfs_fop_write_iter+0x1b4/0x28c

The write lands one u32 past the end of the allocation.

soc_opp_count is only read a few lines below the loop that fills it, so it never needed static storage. Make it a local.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.