CVE-2021-47012 Information

Description

In the Linux kernel the following vulnerability has been resolved:

RDMA/siw: Fix a use after free in siw_alloc_mr

Our code analyzer reported a UAF.

In siw_alloc_mr() it calls siw_mr_add_mem(mr..). In the implementation of siw_mr_add_mem() mem is assigned to mr->mem and then mem is freed via kfree(mem) if xa_alloc_cyclic() failed. Here mr->mem still point to a freed object. After the execution continue up to the err_out branch of siw_alloc_mr and the freed mr->mem is used in siw_mr_drop_mem(mr).

My patch moves \mr->mem = mem\ behind the if (xa_alloc_cyclic(..)<0) section to avoid the uaf.

Reference

https://git.kernel.org/stable/c/30b9e92d0b5e5d5dc1101ab856c17009537cbca4 https://git.kernel.org/stable/c/608a4b90ece039940e9425ee2b39c8beff27e00c https://git.kernel.org/stable/c/3e22b88e02c194f6c80867abfef5cc09383461f4 https://git.kernel.org/stable/c/ad9ce7188432650469a6c7625bf479f5ed0b6155 https://git.kernel.org/stable/c/3093ee182f01689b89e9f8797b321603e5de4f63