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[ Upstream commit42023d4b6d] 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. Fixes:39e47767ec("rpmsg: Add driver_override device attribute for rpmsg_device") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com> Link: https://lore.kernel.org/r/20251202174948.12693-1-hanguidong02@gmail.com Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>