greybus: Fix use-after-free bug in gb_interface_release due to race condition.

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: greybus: Fix use-after-free bug in gb_interface_release due to race condition. In gb_interface_create, &intf->mode_switch_completion is bound with gb_interface_mode_switch_work. Then it will be started by gb_interface_request_mode_switch. Here is the relevant code. if (!queue_work(system_long_wq, &intf->mode_switch_work)) { ... } If we call gb_interface_release to make cleanup, there may be an unfinished work. This function will call kfree to free the object "intf". However, if gb_interface_mode_switch_work is scheduled to run after kfree, it may cause use-after-free error as gb_interface_mode_switch_work will use the object "intf". The possible execution flow that may lead to the issue is as follows: CPU0 CPU1 | gb_interface_create | gb_interface_request_mode_switch gb_interface_release | kfree(intf) (free) | | gb_interface_mode_switch_work | mutex_lock(&intf->mutex) (use) Fix it by canceling the work before kfree.

References

• https://git.kernel.org/stable/c/74cd0a421896b2e07eafe7da4275302bfecef201
• https://git.kernel.org/stable/c/2b6bb0b4abfd79b8698ee161bb73c0936a2aaf83
• https://git.kernel.org/stable/c/fb071f5c75d4b1c177824de74ee75f9dd34123b9
• https://git.kernel.org/stable/c/9a733d69a4a59c2d08620e6589d823c24be773dc
• https://git.kernel.org/stable/c/0b8fba38bdfb848fac52e71270b2aa3538c996ea
• https://git.kernel.org/stable/c/03ea2b129344152157418929f06726989efc0445
• https://git.kernel.org/stable/c/5c9c5d7f26acc2c669c1dcf57d1bb43ee99220ce