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author | Xi Wang <xi.wang@gmail.com> | 2015-06-25 05:47:39 -0700 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-06-25 14:50:43 +0100 |
commit | 8eee539ddea09bccae2426f09b0ba6a18b72b691 (patch) | |
tree | d72b62bd07f1e0479edc69a0a25860acf5d58bf7 /arch/arm64 | |
parent | be081d9bf3e163a9ed1ca2f0f14f08424c7f9016 (diff) | |
download | linux-8eee539ddea09bccae2426f09b0ba6a18b72b691.tar.gz linux-8eee539ddea09bccae2426f09b0ba6a18b72b691.tar.bz2 linux-8eee539ddea09bccae2426f09b0ba6a18b72b691.zip |
arm64: bpf: fix out-of-bounds read in bpf2a64_offset()
Problems occur when bpf_to or bpf_from has value prog->len - 1 (e.g.,
"Very long jump backwards" in test_bpf where the last instruction is a
jump): since ctx->offset has length prog->len, ctx->offset[bpf_to + 1]
or ctx->offset[bpf_from + 1] will cause an out-of-bounds read, leading
to a bogus jump offset and kernel panic.
This patch moves updating ctx->offset to after calling build_insn(),
and changes indexing to use bpf_to and bpf_from without + 1.
Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler")
Cc: <stable@vger.kernel.org> # 3.18+
Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index dc6a4842683a..c81ddd4ff7f7 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -113,9 +113,9 @@ static inline void emit_a64_mov_i(const int is64, const int reg, static inline int bpf2a64_offset(int bpf_to, int bpf_from, const struct jit_ctx *ctx) { - int to = ctx->offset[bpf_to + 1]; + int to = ctx->offset[bpf_to]; /* -1 to account for the Branch instruction */ - int from = ctx->offset[bpf_from + 1] - 1; + int from = ctx->offset[bpf_from] - 1; return to - from; } @@ -640,10 +640,11 @@ static int build_body(struct jit_ctx *ctx) const struct bpf_insn *insn = &prog->insnsi[i]; int ret; + ret = build_insn(insn, ctx); + if (ctx->image == NULL) ctx->offset[i] = ctx->idx; - ret = build_insn(insn, ctx); if (ret > 0) { i++; continue; |