From: Fabien Parent fabien.parent@linaro.org
commit 01039fb8e90c9cb684430414bff70cea9eb168c5 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/qcom-cpufreq-nvmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/cpufreq/qcom-cpufreq-nvmem.c +++ b/drivers/cpufreq/qcom-cpufreq-nvmem.c @@ -264,7 +264,8 @@ static int qcom_cpufreq_probe(struct pla struct nvmem_cell *speedbin_nvmem; struct device_node *np; struct device *cpu_dev; - char *pvs_name = "speedXX-pvsXX-vXX"; + char pvs_name_buffer[] = "speedXX-pvsXX-vXX"; + char *pvs_name = pvs_name_buffer; unsigned cpu; const struct of_device_id *match; int ret;