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| author | Rabin Vincent <rabin@rab.in> | 2016-01-05 16:23:07 +0100 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-02-15 15:42:43 -0500 |
| commit | 03a115644c4a6dd0f7efec7e9b28b2dbebd7c018 (patch) | |
| tree | 5bd1f74fcc5736fc23f638033bb30020499fe285 /arch/powerpc | |
| parent | 7e95dfd637e49b49f3e3383fc28db48004103184 (diff) | |
| download | lwn-03a115644c4a6dd0f7efec7e9b28b2dbebd7c018.tar.gz lwn-03a115644c4a6dd0f7efec7e9b28b2dbebd7c018.zip | |
net: filter: make JITs zero A for SKF_AD_ALU_XOR_X
[ Upstream commit 55795ef5469290f89f04e12e662ded604909e462 ]
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 <rabin@rab.in>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/net/bpf_jit_comp.c | 13 |
1 files changed, 2 insertions, 11 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index cbae2dfd053c..6a29085dd5a9 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) |