Commit 1e4df6b7 authored by Xi Wang's avatar Xi Wang Committed by Will Deacon

arm64: bpf: fix signedness bug in loading 64-bit immediate

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>
Cc: <stable@vger.kernel.org>
Fixes: 30d3d94c ("arm64: bpf: add 'load 64-bit immediate' instruction")
Signed-off-by: default avatarXi Wang <xi.wang@gmail.com>
[will: removed non-arm64 bits and redundant casting]
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 326a7803
......@@ -487,7 +487,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
return -EINVAL;
}
imm64 = (u64)insn1.imm << 32 | imm;
imm64 = (u64)insn1.imm << 32 | (u32)imm;
emit_a64_mov_i64(dst, imm64, ctx);
return 1;
......
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