CVE-2021-47482

In the Linux kernel, the following vulnerability has been resolved: net: batman-adv: fix error handling Syzbot reported ODEBUG warning in batadv_nc_mesh_free(). The problem was in wrong error handling in batadv_mesh_init(). Before this patch batadv_mesh_init() was calling batadv_mesh_free() in case of any batadv_*_init() calls failure. This approach may work well, when there is some kind of indicator, which can tell which parts of batadv are initialized; but there isn't any. All written above lead to cleaning up uninitialized fields. Even if we hide ODEBUG warning by initializing bat_priv->nc.work, syzbot was able to hit GPF in batadv_nc_purge_paths(), because hash pointer in still NULL. [1] To fix these bugs we can unwind batadv_*_init() calls one by one. It is good approach for 2 reasons: 1) It fixes bugs on error handling path 2) It improves the performance, since we won't call unneeded batadv_*_free() functions. So, this patch makes all batadv_*_init() clean up all allocated memory before returning with an error to no call correspoing batadv_*_free() and open-codes batadv_mesh_free() with proper order to avoid touching uninitialized fields.

In the Linux kernel, the following vulnerability has been resolved: net: batman-adv: fix error handling Syzbot reported ODEBUG warning in batadv_nc_mesh_free(). The problem was in wrong error handling in batadv_mesh_init(). Before this patch batadv_mesh_init() was calling batadv_mesh_free() in case of any batadv_*_init() calls failure. This approach may work well, when there is some kind of indicator, which can tell which parts of batadv are initialized; but there isn't any. All written above lead to cleaning up uninitialized fields. Even if we hide ODEBUG warning by initializing bat_priv->nc.work, syzbot was able to hit GPF in batadv_nc_purge_paths(), because hash pointer in still NULL. [1] To fix these bugs we can unwind batadv_*_init() calls one by one. It is good approach for 2 reasons: 1) It fixes bugs on error handling path 2) It improves the performance, since we won't call unneeded batadv_*_free() functions. So, this patch makes all batadv_*_init() clean up all allocated memory before returning with an error to no call correspoing batadv_*_free() and open-codes batadv_mesh_free() with proper order to avoid touching uninitialized fields.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net: batman-adv: corrección de manejo de errores Syzbot informó advertencia ODEBUG en batadv_nc_mesh_free(). El problema estaba en el manejo incorrecto de errores en batadv_mesh_init(). Antes de este parche, batadv_mesh_init() llamaba a batadv_mesh_free() en caso de que fallara alguna llamada a batadv_*_init(). Este enfoque puede funcionar bien cuando hay algún tipo de indicador que puede indicar qué partes de batadv están inicializadas; pero no hay ninguno. Todo lo escrito anteriormente conduce a la sanitización de campos no inicializados. Incluso si ocultamos la advertencia ODEBUG inicializando bat_priv->nc.work, syzbot pudo presionar GPF en batadv_nc_purge_paths(), porque el puntero hash todavía es NULL. [1] Para corregir estos errores podemos desenredar las llamadas batadv_*_init() una por una. Es un buen enfoque por 2 razones: 1) Corrige errores en la ruta de manejo de errores 2) Mejora el rendimiento, ya que no llamaremos a funciones batadv_*_free() innecesarias. Entonces, este parche hace que batadv_*_init() limpie toda la memoria asignada antes de regresar con un error de no llamada correspondiente a batadv_*_free() y códigos abiertos batadv_mesh_free() con el orden adecuado para evitar tocar campos no inicializados.