RDMA/uverbs: Prevent integer overflow issue

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Prevent integer overflow issue In the expression "cmd.wqe_size * cmd.wr_count", both variables are u32 values that come from the user so the multiplication can lead to integer wrapping. Then we pass the result to uverbs_request_next_ptr() which also could potentially wrap. The "cmd.sge_count * sizeof(struct ib_uverbs_sge)" multiplication can also overflow on 32bit systems although it's fine on 64bit systems. This patch does two things. First, I've re-arranged the condition in uverbs_request_next_ptr() so that the use controlled variable "len" is on one side of the comparison by itself without any math. Then I've modified all the callers to use size_mul() for the multiplications.

References

• https://git.kernel.org/stable/c/c57721b24bd897338a81a0ca5fff41600f0f1ad1
• https://git.kernel.org/stable/c/42a6eb4ed7a9a41ba0b83eb0c7e0225b5fca5608
• https://git.kernel.org/stable/c/c2f961c46ea0e5274c5c320d007c2dd949cf627a
• https://git.kernel.org/stable/c/346db03e9926ab7117ed9bf19665699c037c773c
• https://git.kernel.org/stable/c/b92667f755749cf10d9ef1088865c555ae83ffb7
• https://git.kernel.org/stable/c/b3ef4ae713360501182695dd47d6b4f6e1a43eb8
• https://git.kernel.org/stable/c/d0257e089d1bbd35c69b6c97ff73e3690ab149a9