[PULL,02/21] hw/gpio: npcm7xx: fixup out-of-bounds access

Commit Message

Peter Maydell March 7, 2025, 3:06 p.m. UTC

From: Patrick Venture <[e-mail]>

The reg isn't validated to be a possible register before
it's dereferenced for one case.  The mmio space registered
for the gpio device is 4KiB but there aren't that many
registers in the struct.

Cc: [e-mail]
Fixes: 526dbbe0874 ("hw/gpio: Add GPIO model for Nuvoton NPCM7xx")
Signed-off-by: Patrick Venture <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Message-id: [e-mail]
Signed-off-by: Peter Maydell <[e-mail]>
---
 hw/gpio/npcm7xx_gpio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Patch

diff --git a/hw/gpio/npcm7xx_gpio.c b/hw/gpio/npcm7xx_gpio.c
index 23e67424c9f..2916056fae6 100644
--- a/hw/gpio/npcm7xx_gpio.c
+++ b/hw/gpio/npcm7xx_gpio.c
@@ -220,8 +220,6 @@  static void npcm7xx_gpio_regs_write(void *opaque, hwaddr addr, uint64_t v,
         return;
     }
 
-    diff = s->regs[reg] ^ value;
-
     switch (reg) {
     case NPCM7XX_GPIO_TLOCK1:
     case NPCM7XX_GPIO_TLOCK2:
@@ -242,6 +240,7 @@  static void npcm7xx_gpio_regs_write(void *opaque, hwaddr addr, uint64_t v,
     case NPCM7XX_GPIO_PU:
     case NPCM7XX_GPIO_PD:
     case NPCM7XX_GPIO_IEM:
+        diff = s->regs[reg] ^ value;
         s->regs[reg] = value;
         npcm7xx_gpio_update_pins(s, diff);
         break;