[PATCH 4.9 08/24] ARM: vexpress/spc: Avoid negative array index when !SMP

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Kees Cook <keescook@chromium.org>

[ Upstream commit b3f1dd52c991d79118f35e6d1bf4d7cb09882e38 ]

When building multi_v7_defconfig+CONFIG_SMP=n, -Warray-bounds exposes
a couple negative array index accesses:

arch/arm/mach-vexpress/spc.c: In function 've_spc_clk_init':
arch/arm/mach-vexpress/spc.c:583:21: warning: array subscript -1 is below array bounds of 'bool[2]' {aka '_Bool[2]'} [-Warray-bounds]
  583 |   if (init_opp_table[cluster])
      |       ~~~~~~~~~~~~~~^~~~~~~~~
arch/arm/mach-vexpress/spc.c:556:7: note: while referencing 'init_opp_table'
  556 |  bool init_opp_table[MAX_CLUSTERS] = { false };
      |       ^~~~~~~~~~~~~~
arch/arm/mach-vexpress/spc.c:592:18: warning: array subscript -1 is below array bounds of 'bool[2]' {aka '_Bool[2]'} [-Warray-bounds]
  592 |    init_opp_table[cluster] = true;
      |    ~~~~~~~~~~~~~~^~~~~~~~~
arch/arm/mach-vexpress/spc.c:556:7: note: while referencing 'init_opp_table'
  556 |  bool init_opp_table[MAX_CLUSTERS] = { false };
      |       ^~~~~~~~~~~~~~

Skip this logic when built !SMP.

Link: https://lore.kernel.org/r/20220331190443.851661-1-keescook@chromium.org
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/mach-vexpress/spc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-vexpress/spc.c b/arch/arm/mach-vexpress/spc.c
index 635b0d549487..c16f39614003 100644
--- a/arch/arm/mach-vexpress/spc.c
+++ b/arch/arm/mach-vexpress/spc.c
@@ -584,7 +584,7 @@ static int __init ve_spc_clk_init(void)
 		}
 
 		cluster = topology_physical_package_id(cpu_dev->id);
-		if (init_opp_table[cluster])
+		if (cluster < 0 || init_opp_table[cluster])
 			continue;
 
 		if (ve_init_opp_table(cpu_dev))
-- 
2.35.1