CVE-2021-47549

En el kernel de Linux se ha resuelto la siguiente vulnerabilidad: sata_fsl: corrige UAF en sata_fsl_port_stop cuando rmmod sata_fsl Cuando se ejecuta el comando `rmmod sata_fsl.ko` en el PPC64 GNU/Linux se reporta un error: ====== ==================================================== ========== ERROR: No se puede manejar el acceso a los datos del kernel al leer en 0x80000800805b502c Ups: Acceso al kernel del área defectuosa, firma: 11 [#1] NIP [c0000000000388a4] .ioread32+0x4/0x20 LR [80000000000c6034 ] .sata_fsl_port_stop+0x44/0xe0 [sata_fsl] Seguimiento de llamadas: .free_irq+0x1c/0x4e0 (no confiable) .ata_host_stop+0x74/0xd0 [libata] .release_nodes+0x330/0x3f0 .device_release_driver_internal+0x178/0x2c0. driver_detach+0x64/0xd0 . bus_remove_driver+0x70/0xf0 .driver_unregister+0x38/0x80 .platform_driver_unregister+0x14/0x30 .fsl_sata_driver_exit+0x18/0xa20 [sata_fsl] .__se_sys_delete_module+0x1ec/0x2d0 .system_call_exception+ 0xfc/0x1f0 system_call_common+0xf8/0x200 ======= ==================================================== ========= La activación del ERROR se muestra en la siguiente pila: driver_detach device_release_driver_internal __device_release_driver drv->remove(dev) --> platform_drv_remove/platform_remove drv->remove(dev) --> sata_fsl_remove iounmap( host_priv->hcr_base); <---- desasignar kfree(host_priv); <---- free devres_release_all release_nodes dr->node.release(dev, dr->data) --> ata_host_stop ap->ops->port_stop(ap) --> sata_fsl_port_stop ioread32(hcr_base + HCONTROL) <--- - UAF host->ops->host_stop(host) Las funciones iounmap(host_priv->hcr_base) y kfree(host_priv) no deben ejecutarse en drv->remove. Estas funciones deben ejecutarse en host_stop después de port_stop. Por lo tanto, movemos estas funciones a la nueva función sata_fsl_host_stop y vinculamos la nueva función a host_stop.

In the Linux kernel, the following vulnerability has been resolved: sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl When the `rmmod sata_fsl.ko` command is executed in the PPC64 GNU/Linux, a bug is reported: ================================================================== BUG: Unable to handle kernel data access on read at 0x80000800805b502c Oops: Kernel access of bad area, sig: 11 [#1] NIP [c0000000000388a4] .ioread32+0x4/0x20 LR [80000000000c6034] .sata_fsl_port_stop+0x44/0xe0 [sata_fsl] Call Trace: .free_irq+0x1c/0x4e0 (unreliable) .ata_host_stop+0x74/0xd0 [libata] .release_nodes+0x330/0x3f0 .device_release_driver_internal+0x178/0x2c0 .driver_detach+0x64/0xd0 .bus_remove_driver+0x70/0xf0 .driver_unregister+0x38/0x80 .platform_driver_unregister+0x14/0x30 .fsl_sata_driver_exit+0x18/0xa20 [sata_fsl] .__se_sys_delete_module+0x1ec/0x2d0 .system_call_exception+0xfc/0x1f0 system_call_common+0xf8/0x200 ================================================================== The triggering of the BUG is shown in the following stack: driver_detach device_release_driver_internal __device_release_driver drv->remove(dev) --> platform_drv_remove/platform_remove drv->remove(dev) --> sata_fsl_remove iounmap(host_priv->hcr_base); <---- unmap kfree(host_priv); <---- free devres_release_all release_nodes dr->node.release(dev, dr->data) --> ata_host_stop ap->ops->port_stop(ap) --> sata_fsl_port_stop ioread32(hcr_base + HCONTROL) <---- UAF host->ops->host_stop(host) The iounmap(host_priv->hcr_base) and kfree(host_priv) functions should not be executed in drv->remove. These functions should be executed in host_stop after port_stop. Therefore, we move these functions to the new function sata_fsl_host_stop and bind the new function to host_stop.