ARM: OMAP2+: Fix -Warray-bounds warning in _pwrdm_state_switch()

If function pwrdm_read_prev_pwrst() returns -EINVAL, we will end
up accessing array pwrdm->state_counter through negative index
-22. This is wrong and the compiler is legitimately warning us
about this potential problem.

Fix this by sanity checking the value stored in variable _prev_
before accessing array pwrdm->state_counter.

Address the following -Warray-bounds warning:
arch/arm/mach-omap2/powerdomain.c:178:45: warning: array subscript -22 is below array bounds of 'unsigned int[4]' [-Warray-bounds]

Link: https://github.com/KSPP/linux/issues/307
Fixes: ba20bb126940 ("OMAP: PM counter infrastructure.")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/20230607050639.LzbPn%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Message-ID: <ZIFVGwImU3kpaGeH@work>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
index 777f9f8..5e05dd1 100644 (file)
--- a/arch/arm/mach-omap2/powerdomain.c
+++ b/arch/arm/mach-omap2/powerdomain.c
@@ -174,7 +174,7 @@ static int _pwrdm_state_switch(struct powerdomain *pwrdm, int flag)
                break;
        case PWRDM_STATE_PREV:
                prev = pwrdm_read_prev_pwrst(pwrdm);
-               if (pwrdm->state != prev)
+               if (prev >= 0 && pwrdm->state != prev)
                        pwrdm->state_counter[prev]++;
                if (prev == PWRDM_POWER_RET)
                        _update_logic_membank_counters(pwrdm);