CVE-2024-49874

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

i3c: master: svc: Fix use after free vulnerability in svc_i3c_master Driver Due to Race Condition

In the svc_i3c_master_probe function, &master->hj_work is bound with svc_i3c_master_hj_work, &master->ibi_work is bound with svc_i3c_master_ibi_work. And svc_i3c_master_ibi_work can start the hj_work, svc_i3c_master_irq_handler can start the ibi_work.

If we remove the module which will call svc_i3c_master_remove to make cleanup, it will free master->base through i3c_master_unregister while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows:

CPU0 CPU1

                                | svc_i3c_master_hj_work

svc_i3c_master_remove | i3c_master_unregister(&master->base)| device_unregister(&master->dev) | device_release | //free master->base | | i3c_master_do_daa(&master->base) | //use master->base

Fix it by ensuring that the work is canceled before proceeding with the cleanup in svc_i3c_master_remove.

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References

• https://git.kernel.org/stable/c/27b55724d3f781dd6e635e89dc6e2fd78fa81a00
• https://git.kernel.org/stable/c/4318998892bf8fe99f97bea18c37ae7b685af75a
• https://git.kernel.org/stable/c/4ac637122930cc4ab7e2c22e364cf3aaf96b05b1
• https://git.kernel.org/stable/c/56bddf543d4d7ddeff3f87b554ddacfdf086bffe
• https://git.kernel.org/stable/c/61850725779709369c7e907ae8c7c75dc7cec4f3