[PATCH 5.10 303/406] cpufreq: brcmstb-avs-cpufreq: Fix -Warray-bounds bug

Greg Kroah-Hartman
2023-09-17T19:37:32Z

From: Gustavo A. R. Silva <gustavoars@kernel.org>

commit e520d0b6be950ce3738cf4b9bd3b392be818f1dc upstream.

Allocate extra space for terminating element at:

drivers/cpufreq/brcmstb-avs-cpufreq.c:
449 table[i].frequency = CPUFREQ_TABLE_END;

and add code comment to make this clear.

This fixes the following -Warray-bounds warning seen after building
ARM with multi_v7_defconfig (GCC 13):
In function 'brcm_avs_get_freq_table',
inlined from 'brcm_avs_cpufreq_init' at drivers/cpufreq/brcmstb-avs-cpufreq.c:623:15:
drivers/cpufreq/brcmstb-avs-cpufreq.c:449:28: warning: array subscript 5 is outside array bounds of 'void[60]' [-Warray-bounds=]
449 | table[i].frequency = CPUFREQ_TABLE_END;
In file included from include/linux/node.h:18,
from include/linux/cpu.h:17,
from include/linux/cpufreq.h:12,
from drivers/cpufreq/brcmstb-avs-cpufreq.c:44:
In function 'devm_kmalloc_array',
inlined from 'devm_kcalloc' at include/linux/device.h:328:9,
inlined from 'brcm_avs_get_freq_table' at drivers/cpufreq/brcmstb-avs-cpufreq.c:437:10,
inlined from 'brcm_avs_cpufreq_init' at drivers/cpufreq/brcmstb-avs-cpufreq.c:623:15:
include/linux/device.h:323:16: note: at offset 60 into object of size 60 allocated by 'devm_kmalloc'
323 | return devm_kmalloc(dev, bytes, flags);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -Warray-bounds.

Link: https://github.com/KSPP/linux/issues/324
Fixes: de322e085995 ("cpufreq: brcmstb-avs-cpufreq: AVS CPUfreq driver for Broadcom STB SoCs")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/cpufreq/brcmstb-avs-cpufreq.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/cpufreq/brcmstb-avs-cpufreq.c
+++ b/drivers/cpufreq/brcmstb-avs-cpufreq.c
@@ -434,7 +434,11 @@ brcm_avs_get_freq_table(struct device *d
if (ret)
return ERR_PTR(ret);

- table = devm_kcalloc(dev, AVS_PSTATE_MAX + 1, sizeof(*table),
+ /*
+ * We allocate space for the 5 different P-STATES AVS,
+ * plus extra space for a terminating element.
+ */
+ table = devm_kcalloc(dev, AVS_PSTATE_MAX + 1 + 1, sizeof(*table),
GFP_KERNEL);
if (!table)
return ERR_PTR(-ENOMEM);