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

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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: 30d3d94cc3 ("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>
This commit is contained in:
Xi Wang 2015-05-08 06:39:51 +01:00 committed by Will Deacon
parent 326a780317
commit 1e4df6b720
1 changed files with 1 additions and 1 deletions
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2
arch/arm64/net/bpf_jit_comp.c
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@ -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;