CVE-2025-71274

In the Linux kernel, the following vulnerability has been resolved:

rpmsg: core: fix race in driver_override_show() and use core helper

The driver_override_show function reads the driver_override string

without holding the device_lock. However, the store function modifies

and frees the string while holding the device_lock. This creates a race

condition where the string can be freed by the store function while

being read by the show function, leading to a use-after-free.

To fix this, replace the rpmsg_string_attr macro with explicit show and

store functions. The new driver_override_store uses the standard

driver_set_override helper. Since the introduction of

driver_set_override, the comments in include/linux/rpmsg.h have stated

that this helper must be used to set or clear driver_override, but the

implementation was not updated until now.

Because driver_set_override modifies and frees the string while holding

the device_lock, the new driver_override_show now correctly holds the

device_lock during the read operation to prevent the race.

Additionally, since rpmsg_string_attr has only ever been used for

driver_override, removing the macro simplifies the code.