From 55795ef5469290f89f04e12e662ded604909e462 Mon Sep 17 00:00:00 2001 From: Rabin Vincent Date: Tue, 5 Jan 2016 16:23:07 +0100 Subject: net: filter: make JITs zero A for SKF_AD_ALU_XOR_X The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data instructions since it XORs A with X while all the others replace A with some loaded value. All the BPF JITs fail to clear A if this is used as the first instruction in a filter. This was found using american fuzzy lop. Add a helper to determine if A needs to be cleared given the first instruction in a filter, and use this in the JITs. Except for ARM, the rest have only been compile-tested. Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum") Signed-off-by: Rabin Vincent Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- arch/powerpc/net/bpf_jit_comp.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) (limited to 'arch/powerpc/net') diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 04782164ee67..2d66a8446198 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -78,18 +78,9 @@ static void bpf_jit_build_prologue(struct bpf_prog *fp, u32 *image, PPC_LI(r_X, 0); } - switch (filter[0].code) { - case BPF_RET | BPF_K: - case BPF_LD | BPF_W | BPF_LEN: - case BPF_LD | BPF_W | BPF_ABS: - case BPF_LD | BPF_H | BPF_ABS: - case BPF_LD | BPF_B | BPF_ABS: - /* first instruction sets A register (or is RET 'constant') */ - break; - default: - /* make sure we dont leak kernel information to user */ + /* make sure we dont leak kernel information to user */ + if (bpf_needs_clear_a(&filter[0])) PPC_LI(r_A, 0); - } } static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) -- cgit v1.2.1