Re: [PATCH] bpf: handle 32-bit zext during constant blinding

[Daniel Borkmann]

On 8/21/19 9:23 PM, Naveen N. Rao wrote:
> Since BPF constant blinding is performed after the verifier pass, the
> ALU32 instructions inserted for doubleword immediate loads don't have a
> corresponding zext instruction. This is causing a kernel oops on powerpc
> and can be reproduced by running 'test_cgroup_storage' with
> bpf_jit_harden=2.
>
> Fix this by emitting BPF_ZEXT during constant blinding if
> prog->aux->verifier_zext is set.
>
> Fixes: a4b1d3c1ddf6cb ("bpf: verifier: insert zero extension according to analysis result")
> Reported-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>

LGTM, applied to bpf, thanks!