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| H A D | qcom-cpufreq-nvmem.c | diff 01039fb8e90c9cb684430414bff70cea9eb168c5 Sat Oct 15 08:04:23 CDT 2022 Fabien Parent <fabien.parent@linaro.org> cpufreq: qcom: fix writes in read-only memory region
This commit fixes a kernel oops because of a write in some read-only memory:
[ 9.068287] Unable to handle kernel write to read-only memory at virtual address ffff800009240ad8
..snip..
[ 9.138790] Internal error: Oops: 9600004f [#1] PREEMPT SMP
..snip..
[ 9.269161] Call trace:
[ 9.276271] __memcpy+0x5c/0x230
[ 9.278531] snprintf+0x58/0x80
[ 9.282002] qcom_cpufreq_msm8939_name_version+0xb4/0x190
[ 9.284869] qcom_cpufreq_probe+0xc8/0x39c
..snip..
The following line defines a pointer that point to a char buffer stored
in read-only memory:
char *pvs_name = "speedXX-pvsXX-vXX";
This pointer is meant to hold a template "speedXX-pvsXX-vXX" where the
XX values get overridden by the qcom_cpufreq_krait_name_version function. Since
the template is actually stored in read-only memory, when the function
executes the following call we get an oops:
snprintf(*pvs_name, sizeof("speedXX-pvsXX-vXX"), "speed%d-pvs%d-v%d",
speed, pvs, pvs_ver);
To fix this issue, we instead store the template name onto the stack by
using the following syntax:
char pvs_name_buffer[] = "speedXX-pvsXX-vXX";
Because the `pvs_name` needs to be able to be assigned to NULL, the
template buffer is stored in the pvs_name_buffer and not under the
pvs_name variable.
Cc: v5.7+ <stable@vger.kernel.org> # v5.7+
Fixes: a8811ec764f9 ("cpufreq: qcom: Add support for krait based socs")
Signed-off-by: Fabien Parent <fabien.parent@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
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