CVE-2025-71274rpmsg: core: fix race in driver_override_show() and use core helper

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/392c6b68334aa0e0ae9aba95c0a366bcb0d92f5d
• https://git.kernel.org/stable/c/d66b8074c555e8abb0ae19eea1c9f3635498bdde
• https://git.kernel.org/stable/c/47615557447185917afa432b7958f87583c417cb
• https://git.kernel.org/stable/c/90c8353f471821d7ccd4fe573a2402e056192494
• https://git.kernel.org/stable/c/7654e6e3cd6bdee9602f6063b3c670bd556d7e61
• https://git.kernel.org/stable/c/2e4a70f3c30910427e5ea848b799066d67b963d5
• https://git.kernel.org/stable/c/954557957177c3c13d7c655976665b1170da5e50
• https://git.kernel.org/stable/c/42023d4b6d2661a40ee2dcf7e1a3528a35c638ca