Re: [RFC v3 04/22] bpf: Set register type according to is_valid_access()

[Thomas Graf]

On 09/14/16 at 09:23am, Mickaël Salaün wrote:
> This fix a pointer leak when an unprivileged eBPF program read a pointer
> value from the context. Even if is_valid_access() returns a pointer
> type, the eBPF verifier replace it with UNKNOWN_VALUE. The register
> value containing an address is then allowed to leak. Moreover, this
> prevented unprivileged eBPF programs to use functions with (legitimate)
> pointer arguments.
> 
> This bug was not a problem until now because the only unprivileged eBPF
> program allowed is of type BPF_PROG_TYPE_SOCKET_FILTER and all the types
> from its context are UNKNOWN_VALUE.
> 
> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx>
> Fixes: 969bf05eb3ce ("bpf: direct packet access")
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>

Can you post this fix separately? It's valid and needed outside of the
scope of this series.