From: Xi Wang <xi.wang@gmail.com>
Date: Thu, 25 Jun 2015 12:47:39 +0000 (-0700)
Subject: arm64: bpf: fix out-of-bounds read in bpf2a64_offset()
X-Git-Tag: omap-for-v4.3/legacy-v2-signed~51^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8eee539ddea09bccae2426f09b0ba6a18b72b691;p=pandora-kernel.git

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>
---

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