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

[Daniel Borkmann]

On 10/19/2016 04:54 PM, Thomas Graf wrote:
> 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.

Yes, that one was already merged:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=1955351da41caa1dbf4139191358fed84909d64b