CVE-2021-47317

In the Linux kernel, the following vulnerability has been resolved:
powerpc/bpf: Fix detecting BPF atomic instructions Commit 91c960b0056672
(“bpf: Rename BPF_XADD and prepare to encode other atomics in .imm”)
converted BPF_XADD to BPF_ATOMIC and added a way to distinguish
instructions based on the immediate field. Existing JIT implementations
were updated to check for the immediate field and to reject programs
utilizing anything more than BPF_ADD (such as BPF_FETCH) in the immediate
field. However, the check added to powerpc64 JIT did not look at the
correct BPF instruction. Due to this, such programs would be accepted and
incorrectly JIT’ed resulting in soft lockups, as seen with the atomic
bounds test. Fix this by looking at the correct immediate value.