[PATCHv2] net: bpf: reject invalid shifts

From: Rabin Vincent <redacted>
Date: Tue, 12 Jan 2016 20:17:08 +0100

On ARM64, a BUG() is triggered in the eBPF JIT if a filter with a
constant shift that can't be encoded in the immediate field of the
UBFM/SBFM instructions is passed to the JIT.  Since these shifts
amounts, which are negative or >= regsize, are invalid, reject them in
the eBPF verifier and the classic BPF filter checker, for all
architectures.

Signed-off-by: Rabin Vincent <redacted>
---
v2: handle BPF_ARSH too

Applied and queued up for -stable, thanks.