encoding/pem: TestFuzz fails again

[rsc]

Apparent repeat of #19829. Maybe I didn't fix it well enough last time.

--- FAIL: TestFuzz (0.00s)
	pem_test.go:242: Encode of &pem.Block{Type:"𥁵\U0005cac4\U0002ddf6\U0010ae54\U000b322e\U000f1bd4\U00073f73:\U000ec347\U0008e656\ue478\U000ee00d鰭𢢗\U000acf01\U00109e18\U000d1766\U00046126", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
FAIL
FAIL	encoding/pem	0.033s

[mvdan]

Another one on linux-amd64: https://storage.googleapis.com/go-build-log/5d3ca2d0/linux-amd64_21491730.log

[iwdgo]

Issue does not appear on 1.10.3 and all tests succeed (Windows).

go test -run=TestFuzz
PASS
ok      .../golang/go/src/encoding/pem    1.062s

[arbrix]

I've reproduced it on go1.11 (darwin/amd64) by stress tool

--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"屗\U0007dd5d\U00053406\U000e7c86𧣳\U000b3b5b\U00064307\U000ffce6𦸚\U0005781d倂\U000d1575\U00081bb0:\U00061bb0\U000a200c\U000b076f\U000a3af1\U00107c9e\U000777e5\U001000a2𢌡\U00068b5f\U000790e4\U000ae845\U000bf94a", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U0010f079\U000a4b4a\U00011f7c\U0001182b:\U0001c8af\U0008cd97\U0006a22a\U00104b8b\U00074b3cᕤ\U0001bfe3\U000de4ec\U000cbd63\uf423\U000f5f6b\U000b6c26\U000ffd28\U00090e86\U0003b003\U000e5294\U000c53af𬈒\U00081e5d\U000316ae\U0004f92d\U0004acf0\U000e8e4f\U0009ec34\U000ab9f5\U000b500f\U0007a161\U0008d652\U000a11bb\U00071097\U0008558f\U000e21e6\U000fc689\U000b1dd2𫋍𒁾", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000389fc\U0010f8d8㫜\U000b52fe𒒟\U00088c67\U000681c8\U0004973d:\U000eb8f4\U000dd900\U00079233\U0009c736\U0010516e\U0008ec0f\U0010e87a\U0004a820\U00016666\U00035115\U000b8c89\U000f5f25\U000fa45f\U00079e0e\U000155f8떽𦄃\U00010f78𝨼\U000ce364\U000b4629\U000c8e7b", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.01s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000b2bb4\U000c180f\U00037c7d朐\U000bc2a1\U0007f1e4\U0003133d\U000a3b76󠄤\U000f5230\U000a6f72\U00089f6b\U000b3b82\U000925d1\U0010fdc2\U000f38ce\U000b92d8\U000d2002\U000b3f46\U000f6dd0\U00092a32\U0005a37a\U000e9657\U000e5779𦗗\U0006bd2a⽇\U0006268e\U00093c43\U00013d3a:", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"𢨞\U000e790c:\U0005dba2\U001087ee\U00086e9d\U000cbb57\U00035df1\U000f6620\U00034b16\U00015f41\U00090d52\U000f1c3d\U000c3185\U0004ce63\U000c2fad\U000e4268\U00071f80\U000abdee\U001048fd\U00016b49\U000a0bc2", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U0006021e\U0005106a\U000f0a84\U000b86bd\U000e1acb\U0010c4d7\U0006e729:\U000e46c0\U00052591\U000b46af\U00090c0e\U000b679a㍶\U000ae0c9\U00012973\U0007a141\U000e587d\U000452ef\U000b2f64\U000a1e70𦙞\U00109c89\U000e1a91\U0008a6ee\U000330dd\U000f6e05\U00036407雸\U00077e0f\U000e570c\U0010ae58\U000f161e𥅀\U000f4c55\U0003a996𦕜\U000c8f94\U000761e9", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"𨩭\U00093c55𦖰\U0003d91a\U000ecf46\U0001fba0\U0003638b戄߉\U0007932b\U000da69c\U00093e4b\U00091d80\U000655e1\U0008d5f9\U0009de49\U000ca027\U00059041\U000c6864𡼅\U0009c33a\U000f5ca1\U000c5a92\U00085772\U000e763d\U0003cad7\U000b79f2\U0003a9f0\U000b16e4\U00101467\U00063655\U0006084e\U000b7ae3\U000fffe6\U000cc904\U001099a7\U00031dd2\U0003c035:\U0010f712\U000bc464𣳀𪜤", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U00048278\U000bfd58:", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U00093bdf\U00095034\U000a7ea3𗻻\U0007120a\U000a40a9\U0009bc78\U0003ac4d\U0010489c\U000f655e\U000ba80b\U0007b095:\U00092725\U000ecaac\U000e4389\U0008d61e\U0010d567\U0004b1a6\U00092a84\U000a50b7\U000ddb4d\U00092466\U000dbd60\U00098fa1\U000967e9\U000a7ee0𝈂\U00061878\U0006f2e6館\U001048e8\U000b1d2e\U000f2e93\U000e9d5b\U000dbbb4\U000c87a3\U0010fa70\U0008f70c\U000ae675\U000adcc0", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000b95d5\U000e7c30\U000a0274\U00054a8e\U0004f45b\U000526fb\U000611a7\U000e9d1a\U00047cfd\U00014a99:\U000ad805𠒫\U000d5e25\U0005a1ce\U0005f523\U000b6668\U000d9e1d\U0003d368\U000ff089\U0010a399𤫫\U000974c8\U00107365\U00048aa9\U000ca913\U000c970a\U000382e8\U000a7f7f嬲", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.01s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U0010ab98\U0005a829\U0009f10b\U00011f2a厐\U00033111:\U0004491d䪪\U00097536\U0003aaa8\U000b82f5\U000dc5e3\U000435f4\U0007f7ff\U00056087\U00084e58\U00058b95\U000d10d8\U00041e61\U001092fc\U0008016c\U000e580d\U000a70d1\U0008e24e\U0010ad39\U001089d2\U000ef40e\U000dc0b9\U000c8bfd\U000ec7e2\U000f8349\U000d69b9\U000f78d1\U000663f8\U000960d9\U00102057🖄", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000c8811\U000dae96\U000fb603\U000d00fc\U00044ba8𮂖\U00042956\U000b2425\U000b509b\U000a9354캅\U0008491c𦅣\U0007df7c\U000c3c1c𦰨\U0008e01d:𡧫\U000c4fdb\U0008fddc\U0008c7d4\U000479a8", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.01s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000aea38\U00062d8d\U000e00a7\U0001be18\U000f7296\U000886dc\U0009b872\U0005501d\U000f3755\U0008b8f7\U000ffc0b\U000b6159\U000f37bd\U000e544e뽒\U00042061\U000f5322\U00074537\U000c5998:\U0010cb38\U0004a547\U00054105\U00105b92", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.01s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000d4f00\U00082f2b\U0009c467\U000abff0\U000ef245\U0005bc71\U000badd4\U0003e922\U0008ee19\U000932cd\U00088093\U0009ed30\U00032d71𧩂\U000eef6d\U000e0984\U0008ef19:𫌞\U000ee94b\U0003ca2a\U0003e63f픖\U000a4a73\U000faba7𩝖\U00086af1\U000e07c9", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)
--- FAIL: TestFuzz (0.00s)
    pem_test.go:242: Encode of &pem.Block{Type:"\U000ca7a2\U000f27e0\U00105f98\U0004d5db\U000d34c6\U00107e07\U0005a262\U000603cf\U00074485\U00089552\U00077f15\U001025fd\U000f95d0\U000f10de\U000136a1\U000b0860䁫\U0007557d\U0003e084\U000b18d8\U000ba474:\U000ed7be𧾾\U00047e51\U00033f24𗓈\U00058f70\U000fe3a8\U000da08a\U000d4951\U0007af1a\U000cdcb7\U0008aa25\U00108630", Headers:map[string]string{}, Bytes:[]uint8{}} decoded as (*pem.Block)(nil)

[arbrix]

After the investigation, I've found that all these cases due to : at the Type section, that lead that the end PEM line processing as Header and break other logic, I suggest changing TestFuzz for mark such cases as invalid.

[gopherbot]

Change https://golang.org/cl/132635 mentions this issue: encoding/pem: PEM type should not contain ':'