Re: [PATCH] arm64: bpf: fix div-by-zero case

From: Daniel Borkmann
Date: Wed Nov 04 2015 - 14:39:33 EST


On 11/04/2015 07:41 PM, Shi, Yang wrote:
...
Agreed, and we may need add one more test cases in test_bpf module to cover
MOD?

Let me know if you have a test case ready :)

Does the below change look like a valid test?

+ "MOD default X",
+ .u.insns = {
+ /*
+ * A = 0x42
+ * A = A mod X ; this halt the filter execution if X is 0
+ * ret 0x42
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x42),
+ BPF_STMT(BPF_ALU | BPF_MOD | BPF_X, 0),
+ BPF_STMT(BPF_RET | BPF_K, 0x42),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },
+ {
+ "MOD default A",
+ .u.insns = {
+ /*
+ * A = A mod 1
+ * ret A
+ */
+ BPF_STMT(BPF_ALU | BPF_MOD | BPF_K, 0x1),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },

My test result with it:
test_bpf: #284 MOD default X jited:1 ret 66 != 0 FAIL (1 times)
test_bpf: #285 MOD default A jited:1 102 PASS

If it looks right, I will post a patch to add the test cases.

Looks good to me.

Thanks,
Daniel
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