RDMA/hfi1: Fix use-after-free bug for mm struct

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/hfi1: Fix use-after-free bug for mm struct Under certain conditions, such as MPI_Abort, the hfi1 cleanup code may represent the last reference held on the task mm. hfi1_mmu_rb_unregister() then drops the last reference and the mm is freed before the final use in hfi1_release_user_pages(). A new task may allocate the mm structure while it is still being used, resulting in problems. One manifestation is corruption of the mmap_sem counter leading to a hang in down_write(). Another is corruption of an mm struct that is in use by another task.

References

• https://git.kernel.org/stable/c/5f54364ff6cfcd14cddf5441c4a490bb28dd69f7
• https://git.kernel.org/stable/c/9ca11bd8222a612de0d2f54d050bfcf61ae2883f
• https://git.kernel.org/stable/c/0b7186d657ee55e2cdefae498f07d5c1961e8023
• https://git.kernel.org/stable/c/5a9a1b24ddb510715f8f621263938186579a965c
• https://git.kernel.org/stable/c/2bbac98d0930e8161b1957dc0ec99de39ade1b3c