bpf: enforce correct alignment for instructions

After commit 9facc336876f ("bpf: reject any prog that failed read-only lock")
offsetof(struct bpf_binary_header, image) became 3 instead of 4,
breaking powerpc BPF badly, since instructions need to be word aligned.

Fixes: 9facc336876f ("bpf: reject any prog that failed read-only lock")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index b615df5..20f2659 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -472,7 +472,9 @@ struct sock_fprog_kern {
 struct bpf_binary_header {
        u16 pages;
        u16 locked:1;
-       u8 image[];
+
+       /* Some arches need word alignment for their instructions */
+       u8 image[] __aligned(4);
 };
 
 struct bpf_prog {