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.

Fixes: b4573d1d657a ("cpufreq: imx6q: correct VDDSOC/PU voltage scaling when cpufreq is changed")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

0 files changed, 0 insertions, 0 deletions