CVE-2021-47276

In the Linux kernel, the following vulnerability has been resolved: ftrace: Do not blindly read the ip address in ftrace_bug() It was reported that a bug on arm64 caused a bad ip address to be used for updating into a nop in ftrace_init(), but the error path (rightfully) returned -EINVAL and not -EFAULT, as the bug caused more than one error to occur. But because -EINVAL was returned, the ftrace_bug() tried to report what was at the location of the ip address, and read it directly. This caused the machine to panic, as the ip was not pointing to a valid memory address. Instead, read the ip address with copy_from_kernel_nofault() to safely access the memory, and if it faults, report that the address faulted, otherwise report what was in that location.

In the Linux kernel, the following vulnerability has been resolved: ftrace: Do not blindly read the ip address in ftrace_bug() It was reported that a bug on arm64 caused a bad ip address to be used for updating into a nop in ftrace_init(), but the error path (rightfully) returned -EINVAL and not -EFAULT, as the bug caused more than one error to occur. But because -EINVAL was returned, the ftrace_bug() tried to report what was at the location of the ip address, and read it directly. This caused the machine to panic, as the ip was not pointing to a valid memory address. Instead, read the ip address with copy_from_kernel_nofault() to safely access the memory, and if it faults, report that the address faulted, otherwise report what was in that location.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ftrace: no lea ciegamente la dirección IP en ftrace_bug(). Se informó que un error en arm64 provocó que se usara una dirección IP incorrecta para actualizar a un nop en ftrace_init() , pero la ruta de error (con razón) devolvió -EINVAL y no -EFAULT, ya que el error provocó que ocurriera más de un error. Pero debido a que se devolvió -EINVAL, ftrace_bug() intentó informar qué había en la ubicación de la dirección IP y leerlo directamente. Esto provocó que la máquina entrara en pánico, ya que la IP no apuntaba a una dirección de memoria válida. En su lugar, lea la dirección IP con copy_from_kernel_nofault() para acceder de forma segura a la memoria y, si falla, informe que la dirección falló; de lo contrario, informe qué había en esa ubicación.