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| author | Rabin Vincent <rabin@rab.in> | 2016-01-05 16:23:07 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-31 11:23:36 -0800 |
| commit | 5596242a6263ece70ee14f3b6861f02b8dc82d11 (patch) | |
| tree | 72a12bd35b834cebd31fa8d1cc428a7279bab74d /arch/powerpc | |
| parent | a6b1d24893805bb4f2e7c7bc6f86a98ec37065ee (diff) | |
| download | lwn-5596242a6263ece70ee14f3b6861f02b8dc82d11.tar.gz lwn-5596242a6263ece70ee14f3b6861f02b8dc82d11.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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 17cea18a09d3..264c473c1b3c 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) |