From: Eric Dumazet <edumazet@google.com>
Date: Thu, 21 Jun 2018 00:24:09 +0000 (-0700)
Subject: bpf: enforce correct alignment for instructions
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9262478220eac908ae6e168c3df2c453c87e2da3;p=linux.git

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 b615df57b7d5b..20f2659dd8292 100644
--- 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 {