From 10528b9c45cfb9e8f45217ef2f5ef8b876bbd3f5 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Fri, 13 Jan 2017 22:40:01 +0530 Subject: [PATCH] powerpc/bpf: Flush the entire JIT buffer With bpf_jit_binary_alloc(), we allocate at a page granularity and fill the rest of the space with illegal instructions to mitigate BPF spraying attacks, while having the actual JIT'ed BPF program at a random location within the allocated space. Under this scenario, it would be better to flush the entire allocated buffer rather than just the part containing the actual program. We already flush the buffer from start to the end of the BPF program. Extend this to include the illegal instructions after the BPF program. Signed-off-by: Naveen N. Rao Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: Michael Ellerman --- arch/powerpc/net/bpf_jit_comp64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 935a10f77cfe..d4ed7a0872b1 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -1046,8 +1046,6 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) */ bpf_jit_dump(flen, proglen, pass, code_base); - bpf_flush_icache(bpf_hdr, image + alloclen); - #ifdef PPC64_ELF_ABI_v1 /* Function descriptor nastiness: Address + TOC */ ((u64 *)image)[0] = (u64)code_base; @@ -1057,6 +1055,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) fp->bpf_func = (void *)image; fp->jited = 1; + bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE)); + out: kfree(addrs); -- GitLab