ntb: ntb_hw_switchtec: Fix use after free vulnerability in switchtec_ntb_remove due to race condition

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ntb: ntb_hw_switchtec: Fix use after free vulnerability in switchtec_ntb_remove due to race condition In the switchtec_ntb_add function, it can call switchtec_ntb_init_sndev function, then &sndev->check_link_status_work is bound with check_link_status_work. switchtec_ntb_link_notification may be called to start the work. If we remove the module which will call switchtec_ntb_remove to make cleanup, it will free sndev through kfree(sndev), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows: CPU0 CPU1 | check_link_status_work switchtec_ntb_remove | kfree(sndev); | | if (sndev->link_force_down) | // use sndev Fix it by ensuring that the work is canceled before proceeding with the cleanup in switchtec_ntb_remove.

References

• https://git.kernel.org/stable/c/5126d8f5567f49b52e21fca320eaa97977055099
• https://git.kernel.org/stable/c/b650189687822b705711f0567a65a164a314d8df
• https://git.kernel.org/stable/c/92728fceefdaa2a0a3aae675f86193b006eeaa43
• https://git.kernel.org/stable/c/3ae45be8492460a35b5aebf6acac1f1d32708946
• https://git.kernel.org/stable/c/fa840ba4bd9f3bad7f104e5b32028ee73af8b3dd
• https://git.kernel.org/stable/c/177925d9c8715a897bb79eca62628862213ba956
• https://git.kernel.org/stable/c/e51aded92d42784313ba16c12f4f88cc4f973bbb