CVE-2021-47413

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: usb: chipidea: ci_hdrc_imx: también busque 'phys' phandle. Al pasar 'phys' en el árbol de dispositivos para describir el phandle USB PHY (que es la forma recomendada según Documentation/devicetree /bindings/usb/ci-hdrc-usb2.txt) se observa la siguiente desreferencia del puntero NULL en i.MX7 e i.MX8MM: [1.489344] No se puede manejar la desreferencia del puntero NULL del kernel en la dirección virtual 00000000000000098 [1.498170] Información de cancelación de memoria: [ 1.500966] ESR = 0x96000044 [ 1.504030] EC = 0x25: DABT (EL actual), IL = 32 bits [ 1.509356] SET = 0, FnV = 0 [ 1.512416] EA = 0, S1PTW = 0 [ 1.515569] FSC = 0x04: error de traducción de nivel 0 [1.520458] Información de cancelación de datos: [1.523349] ISV = 0, ISS = 0x00000044 [1.527196] CM = 0, WnR = 1 [1.530176] [0000000000000098] dirección de usuario pero active_mm es intercambiador [1.536544 ] Error interno: Ups : 96000044 [#1] PREEMPT SMP [ 1.542125] Módulos vinculados en: [ 1.545190] CPU: 3 PID: 7 Comm: kworker/u8:0 Not tainted 5.14.0-dirty #3 [ 1.551901] Nombre de hardware: Kontron i.MX8MM N801X S (DT) [1.557133] Cola de trabajo: events_unbound deferred_probe_work_func [1.562984] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) [1.568998] pc: imx7d_charger_detection+0x3f0/0x510 [ 1. 573973] lr: imx7d_charger_detection+0x22c /0x510 Esto sucede porque las funciones del cargador verifican la presencia de phy dentro de la estructura imx_usbmisc_data (data->usb_phy), pero el núcleo chipidea llena el usb_phy pasado a través de 'phys' dentro de 'struct ci_hdrc' (ci->usb_phy). Esto provoca la desreferencia del puntero NULL dentro de imx7d_charger_detection(). Solucione el problema buscando también 'phys' en caso de que no se encuentre 'fsl,usbphy'. Probado en una placa imx7s-warp.

In the Linux kernel, the following vulnerability has been resolved: usb: chipidea: ci_hdrc_imx: Also search for 'phys' phandle When passing 'phys' in the devicetree to describe the USB PHY phandle (which is the recommended way according to Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt) the following NULL pointer dereference is observed on i.MX7 and i.MX8MM: [ 1.489344] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098 [ 1.498170] Mem abort info: [ 1.500966] ESR = 0x96000044 [ 1.504030] EC = 0x25: DABT (current EL), IL = 32 bits [ 1.509356] SET = 0, FnV = 0 [ 1.512416] EA = 0, S1PTW = 0 [ 1.515569] FSC = 0x04: level 0 translation fault [ 1.520458] Data abort info: [ 1.523349] ISV = 0, ISS = 0x00000044 [ 1.527196] CM = 0, WnR = 1 [ 1.530176] [0000000000000098] user address but active_mm is swapper [ 1.536544] Internal error: Oops: 96000044 [#1] PREEMPT SMP [ 1.542125] Modules linked in: [ 1.545190] CPU: 3 PID: 7 Comm: kworker/u8:0 Not tainted 5.14.0-dirty #3 [ 1.551901] Hardware name: Kontron i.MX8MM N801X S (DT) [ 1.557133] Workqueue: events_unbound deferred_probe_work_func [ 1.562984] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) [ 1.568998] pc : imx7d_charger_detection+0x3f0/0x510 [ 1.573973] lr : imx7d_charger_detection+0x22c/0x510 This happens because the charger functions check for the phy presence inside the imx_usbmisc_data structure (data->usb_phy), but the chipidea core populates the usb_phy passed via 'phys' inside 'struct ci_hdrc' (ci->usb_phy) instead. This causes the NULL pointer dereference inside imx7d_charger_detection(). Fix it by also searching for 'phys' in case 'fsl,usbphy' is not found. Tested on a imx7s-warp board.