Re: [PATCH v3] hw/gpio/aspeed: Add reg_table_size to AspeedGPIOClass

[Andrew Jeffery <andrew@codeconstruct.com.au>]

On Wed, 2024-06-19 at 20:36 +0200, Zheyu Ma wrote:
> ASan detected a global-buffer-overflow error in the aspeed_gpio_read()
> function. This issue occurred when reading beyond the bounds of the
> reg_table.
> 
> To enhance the safety and maintainability of the Aspeed GPIO code, this commit
> introduces a reg_table_size member to the AspeedGPIOClass structure. This
> change ensures that the size of the GPIO register table is explicitly tracked
> and initialized, reducing the risk of errors if new register tables are
> introduced in the future.
> 
> Reproducer:
> cat << EOF | qemu-system-aarch64 -display none \
> -machine accel=qtest, -m 512M -machine ast1030-evb -qtest stdio
> readq 0x7e780272
> EOF
> 
> ASAN log indicating the issue:
> ==2602930==ERROR: AddressSanitizer: global-buffer-overflow on address 0x55a5da29e128 at pc 0x55a5d700dc62 bp 0x7fff096c4e90 sp 0x7fff096c4e88
> READ of size 2 at 0x55a5da29e128 thread T0
>     #0 0x55a5d700dc61 in aspeed_gpio_read hw/gpio/aspeed_gpio.c:564:14
>     #1 0x55a5d933f3ab in memory_region_read_accessor system/memory.c:445:11
>     #2 0x55a5d92fba40 in access_with_adjusted_size system/memory.c:573:18
>     #3 0x55a5d92f842c in memory_region_dispatch_read1 system/memory.c:1426:16
>     #4 0x55a5d92f7b68 in memory_region_dispatch_read system/memory.c:1459:9
>     #5 0x55a5d9376ad1 in flatview_read_continue_step system/physmem.c:2836:18
>     #6 0x55a5d9376399 in flatview_read_continue system/physmem.c:2877:19
>     #7 0x55a5d93775b8 in flatview_read system/physmem.c:2907:12
> 
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>

Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>

> ---
> Changes in v3:
> - Add the reproducer
> 
> Changes in v2:
> - Introduce the reg_table_size to AspeedGPIOClass
> ---
>  hw/gpio/aspeed_gpio.c         | 17 +++++++++++++++++
>  include/hw/gpio/aspeed_gpio.h |  1 +
>  2 files changed, 18 insertions(+)
> 
> diff --git a/hw/gpio/aspeed_gpio.c b/hw/gpio/aspeed_gpio.c
> index c1781e2ba3..fd4912edae 100644
> --- a/hw/gpio/aspeed_gpio.c
> +++ b/hw/gpio/aspeed_gpio.c
> @@ -559,6 +559,12 @@ static uint64_t aspeed_gpio_read(void *opaque, hwaddr offset, uint32_t size)
>          return debounce_value;
>      }
>  
> +    if (idx >= agc->reg_table_size) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: idx 0x%" PRIx64 " out of bounds\n",
> +                      __func__, idx);
> +        return 0;
> +    }
> +
>      reg = &agc->reg_table[idx];
>      if (reg->set_idx >= agc->nr_gpio_sets) {
>          qemu_log_mask(LOG_GUEST_ERROR, "%s: no getter for offset 0x%"
> @@ -785,6 +791,12 @@ static void aspeed_gpio_write(void *opaque, hwaddr offset, uint64_t data,
>          return;
>      }
>  
> +    if (idx >= agc->reg_table_size) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: idx 0x%" PRIx64 " out of bounds\n",
> +                      __func__, idx);
> +        return;
> +    }
> +
>      reg = &agc->reg_table[idx];
>      if (reg->set_idx >= agc->nr_gpio_sets) {
>          qemu_log_mask(LOG_GUEST_ERROR, "%s: no setter for offset 0x%"
> @@ -1117,6 +1129,7 @@ static void aspeed_gpio_ast2400_class_init(ObjectClass *klass, void *data)
>      agc->nr_gpio_pins = 216;
>      agc->nr_gpio_sets = 7;
>      agc->reg_table = aspeed_3_3v_gpios;
> +    agc->reg_table_size = GPIO_3_3V_REG_ARRAY_SIZE;
>  }
>  
>  static void aspeed_gpio_2500_class_init(ObjectClass *klass, void *data)
> @@ -1127,6 +1140,7 @@ static void aspeed_gpio_2500_class_init(ObjectClass *klass, void *data)
>      agc->nr_gpio_pins = 228;
>      agc->nr_gpio_sets = 8;
>      agc->reg_table = aspeed_3_3v_gpios;
> +    agc->reg_table_size = GPIO_3_3V_REG_ARRAY_SIZE;
>  }
>  
>  static void aspeed_gpio_ast2600_3_3v_class_init(ObjectClass *klass, void *data)
> @@ -1137,6 +1151,7 @@ static void aspeed_gpio_ast2600_3_3v_class_init(ObjectClass *klass, void *data)
>      agc->nr_gpio_pins = 208;
>      agc->nr_gpio_sets = 7;
>      agc->reg_table = aspeed_3_3v_gpios;
> +    agc->reg_table_size = GPIO_3_3V_REG_ARRAY_SIZE;
>  }
>  
>  static void aspeed_gpio_ast2600_1_8v_class_init(ObjectClass *klass, void *data)
> @@ -1147,6 +1162,7 @@ static void aspeed_gpio_ast2600_1_8v_class_init(ObjectClass *klass, void *data)
>      agc->nr_gpio_pins = 36;
>      agc->nr_gpio_sets = 2;
>      agc->reg_table = aspeed_1_8v_gpios;
> +    agc->reg_table_size = GPIO_1_8V_REG_ARRAY_SIZE;
>  }
>  
>  static void aspeed_gpio_1030_class_init(ObjectClass *klass, void *data)
> @@ -1157,6 +1173,7 @@ static void aspeed_gpio_1030_class_init(ObjectClass *klass, void *data)
>      agc->nr_gpio_pins = 151;
>      agc->nr_gpio_sets = 6;
>      agc->reg_table = aspeed_3_3v_gpios;
> +    agc->reg_table_size = GPIO_3_3V_REG_ARRAY_SIZE;
>  }
>  
>  static const TypeInfo aspeed_gpio_info = {
> diff --git a/include/hw/gpio/aspeed_gpio.h b/include/hw/gpio/aspeed_gpio.h
> index 904eecf62c..e66036ac39 100644
> --- a/include/hw/gpio/aspeed_gpio.h
> +++ b/include/hw/gpio/aspeed_gpio.h
> @@ -75,6 +75,7 @@ struct AspeedGPIOClass {
>      uint32_t nr_gpio_pins;
>      uint32_t nr_gpio_sets;
>      const AspeedGPIOReg *reg_table;
> +    uint32_t reg_table_size;
>  };
>  
>  struct AspeedGPIOState {