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

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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: b4573d1d65 ("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>
This commit is contained in:
Karl Mehltretter
2026-08-06 07:02:39 +02:00
committed by Viresh Kumar
parent 22c23c72c3
commit 8c3afcf27f
1 changed files with 1 additions and 1 deletions
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2
drivers/cpufreq/imx6q-cpufreq.c
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@@ -55,7 +55,6 @@ static unsigned int max_freq;
static unsigned int transition_latency;
static u32 *imx6_soc_volt;
static u32 soc_opp_count;
static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
{
@@ -330,6 +329,7 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
const struct property *prop;
const __be32 *val;
u32 nr, i, j;
u32 soc_opp_count = 0;
cpu_dev = get_cpu_device(0);
if (!cpu_dev) {