From: Daniel Borkmann <dan...@iogearbox.net>
Date: Sun, 15 Jan 2017 01:34:25 +0100
> Make sure that ctx cannot potentially be accessed oob by asserting
> explicitly that ctx access size into pt_regs for BPF_PROG_TYPE_KPROBE
> programs must be within limits. In case some 32bit archs have pt_regs
> not being a multiple of 8, then BPF_DW access could cause such access.
>
> BPF_PROG_TYPE_KPROBE progs don't have a ctx conversion function since
> there's no extra mapping needed. kprobe_prog_is_valid_access() didn't
> enforce sizeof(long) as the only allowed access size, since LLVM can
> generate non BPF_W/BPF_DW access to regs from time to time.
>
> For BPF_PROG_TYPE_TRACEPOINT we don't have a ctx conversion either, so
> add a BUILD_BUG_ON() check to make sure that BPF_DW access will not be
> a similar issue in future (ctx works on event buffer as opposed to
> pt_regs there).
>
> Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to
> kprobes")
> Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
> Acked-by: Alexei Starovoitov <a...@kernel.org>
Applied.
