| From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 043/146] arm64: bpf: fix signedness bug in loading 64-bit immediate | Date | Wed, 17 Jun 2015 15:22:28 -0700 |
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3.19.8-ckt2 -stable review patch. If anyone has any objections, please let me know.
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From: Xi Wang <xi.wang@gmail.com>
commit 1e4df6b7208140f3c49f316d33a409d3a161f350 upstream.
Consider "(u64)insn1.imm << 32 | imm" in the arm64 JIT. Since imm is signed 32-bit, it is sign-extended to 64-bit, losing the high 32 bits. The fix is to convert imm to u32 first, which will be zero-extended to u64 implicitly.
Cc: Zi Shen Lim <zlim.lnx@gmail.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Fixes: 30d3d94cc3d5 ("arm64: bpf: add 'load 64-bit immediate' instruction") Signed-off-by: Xi Wang <xi.wang@gmail.com> [will: removed non-arm64 bits and redundant casting] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/arm64/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index edba042..dc6a484 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -487,7 +487,7 @@ emit_cond_jmp: return -EINVAL; } - imm64 = (u64)insn1.imm << 32 | imm; + imm64 = (u64)insn1.imm << 32 | (u32)imm; emit_a64_mov_i64(dst, imm64, ctx); return 1; -- 1.9.1
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