[Bug] RT-Thread Bouffalo ADC reads outside its DMA sample buffer

Abierto Apto para principiantes
  • ¿Algo no está bien?
#11,949 1 comentario 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 1 día

Nadie ha tomado este issue todavía.

Evaluación

Dificultad
2/5
Tiempo estimado
1-3 horas
Aptitud para principiantes
72/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
c
Área
embedded-iot, security

Línea de trabajo

Lee bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c en las ubicaciones indicadas y sigue cómo se asignan los canales ADC configurados a las posiciones de resultados DMA. Revisa components/drivers/misc/adc.c para entender la ruta pública de lectura y, después, inspecciona la configuración ADC de la placa y las pruebas pertinentes. Se considera terminado cuando se rechazan los canales no admitidos o fuera de rango antes de indexar, y los canales válidos se asignan a las posiciones muestreadas.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

bug
RT-Thread Version

v5.3.0

Affected area

Other / Not sure

Hardware/BSP vendor

Not applicable / Other

Architecture

Not applicable / Other

Board and hardware details

Bouffalo ADC

Develop Toolchain

Other

Describe the bug

RT-Thread Bouffalo ADC reads outside its DMA sample buffer

Affected version

RT-Thread v5.3.0.

Describe the bug

bl_adc_get_value() reads raw_data[10 + channel] without checking the channel. raw_data has 26 words. A channel of 22 selects word 32, past the end of the buffer.

static volatile uint32_t raw_data[16 + 10];

rt_sem_take(_adc->sem, RT_WAITING_FOREVER);
*value = (rt_uint32_t)raw_data[10 + channel];

rt_adc_read() does not validate the channel either. The semaphore is created with an initial count of zero and released from the DMA completion handler, so the read runs after that wait returns. A channel below -10 selects before the start of raw_data.

Staying inside the 26-word array is only the memory bound. A supported channel also has to be one the board actually samples, with a defined slot in the DMA result.

Locations:

bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c:26
bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c:155
bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c:166
bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c:177
bsp/bouffalo_lab/libraries/rt_drivers/drv_adc.c:201
components/drivers/misc/adc.c:118

Threat model

The boundary is a caller of the public ADC API. This report does not treat a network or physical-bus peer as the attacker. The value that caller controls is the channel argument of rt_adc_read(dev, channel). dev only selects the ADC instance. raw_data is a driver buffer; the caller does not supply its address or length.

channel has type rt_int8_t, so the values defined by the API are -128 through 127. The read uses index 10 + channel. Channels 0 through 15 stay inside the 26-word array. Channel 22, which fits in rt_int8_t, selects word 32. A channel below -10 selects before the array. The negative constants RT_ADC_INTERN_CH_TEMPER, RT_ADC_INTERN_CH_VREF, and RT_ADC_INTERN_CH_VBAT (-1, -2, and -3) are inside the array by this formula, but that does not make them valid sample slots.

With RT_USING_FINSH, adc read <channel> passes atoi(argv[2]) into rt_adc_read(). The shell is an entry point only when an untrusted user can reach it. A product task that forwards an untrusted channel into the same API is the same boundary. The read still waits on the ADC semaphore, which starts at zero and is released by the DMA completion handler.

Steps to reproduce

I have not reproduced this on Bouffalo hardware. The reduced check keeps the array length and the 10 + channel index. It does not model the semaphore or DMA.

#include <stdint.h>

static volatile uint32_t raw_data[16 + 10];

static uint32_t read_channel(int8_t channel)
{
    return raw_data[10 + channel];
}

int main(void)
{
    return (int)read_channel(22);
}

Compile it with a bounds sanitizer, for example:

clang -fsanitize=address,undefined -g -O1 repro.c -o repro && ./repro

Rejecting the channel before the index avoids the report. Channel -11 is also out of range; channels 0 and 10 stay inside this array.

Relevant log output

runtime error: index 32 out of bounds for type 'volatile uint32_t[26]'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior

Impact

The callback returns the loaded word through rt_adc_read(). A caller that can supply the channel, including the adc shell command when FinSH is enabled, can request a word outside raw_data once the DMA wait has completed. The reduced check shows the out-of-bounds read. It does not show which adjacent data a product would return, or a network entry point.

This is a read. raw_data is the source, and the store is to the caller's output pointer.

Suggested fix

Validate the channel against the configured channel list before waiting on the semaphore. Map that channel to a documented sample slot and check the slot against the DMA buffer length. Reject negative and unsupported channels. Keep the DMA producer and the reader on the same result layout.

Other additional context

No response

Lenguaje dominante
C
Estrellas
12.3k
Forks
5.5k
Merge medio
4 d 9 h
PR fusionados (30 d)
38

Preparar el entorno

Abrir en Codespaces

Inicia el contenedor de desarrollo del proyecto en tu navegador, con tu propia cuenta de GitHub.

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Más de RT-Thread/rt-thread

Todos los issues de RT-Thread/rt-thread

Issues similares

Más issues de C

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.