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

HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

In the ssi_protocol_probe() function, &ssi->work is bound with ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function within the ssip_pn_ops structure is capable of starting the work.

If we remove the module which will call ssi_protocol_remove() to make a cleanup, it will free ssi through kfree(ssi), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows:

CPU0 CPU1

ssi_protocol_remove | kfree(ssi); | | struct hsi_client *cl = ssi->cl; | // use ssi

Fix it by ensuring that the work is canceled before proceeding with the cleanup in ssi_protocol_remove().