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authorXi Wang <xi.wang@gmail.com>2015-06-25 05:47:39 -0700
committerCatalin Marinas <catalin.marinas@arm.com>2015-06-25 14:50:43 +0100
commit8eee539ddea09bccae2426f09b0ba6a18b72b691 (patch)
treed72b62bd07f1e0479edc69a0a25860acf5d58bf7 /arch/arm64/net/bpf_jit_comp.c
parentARM64: smp: Fix suspicious RCU usage with ipi tracepoints (diff)
downloadlinux-dev-8eee539ddea09bccae2426f09b0ba6a18b72b691.tar.xz
linux-dev-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/net/bpf_jit_comp.c')
-rw-r--r--arch/arm64/net/bpf_jit_comp.c7
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;