add another test for infinite loop found with fuzzing and fix it

fuzz_crashes_test.go

@@ -28,64 +28,29 @@ func TestCrash1(t *testing.T) {
 	}
 }
 
+func parseWithShortTimeout(t *testing.T, test string) {
+	c := make(chan bool, 1)
+	go func() {
+		Parse([]byte(test), nil)
+		c <- true
+	}()
+	select {
+	case <-c:
+	case <-time.After(2 * time.Second):
+		t.Fatalf("timed out parsing %#v\n", test)
+	}
+}
 func TestInfinite1(t *testing.T) {
 	test := "[[[[[[\n\t: ]]]]]]\n\n: " + "\n\n:(()"
-	c := make(chan bool, 1)
-	go func() {
-		Parse([]byte(test), nil)
-		c <- true
-	}()
-	select {
-	case <-c:
-	case <-time.After(2 * time.Second):
-		t.Fatalf("timed out")
-	}
+	parseWithShortTimeout(t, test)
 }
 
-/*
-program hanged (timeout 10 seconds)
-
-SIGABRT: abort
-PC=0x10bf96a m=0 sigcode=0
-
-goroutine 1 [running]:
-github.com/gomarkdown/markdown/ast.LastChild(0x120ea60, 0xc42014b170, 0x120eb20, 0xc42005be00)
-	ast/node.go:349 +0x2a fp=0xc42049dbd0 sp=0xc42049dba0 pc=0x10bf96a
-github.com/gomarkdown/markdown/parser.endsWithBlankLine(0x120ea60, 0xc42014b170, 0x0)
-	parser/block.go:1202 +0x6b fp=0xc42049dc00 sp=0xc42049dbd0 pc=0x10fea0b
-github.com/gomarkdown/markdown/parser.finalizeList.func3(0xc42049dc88, 0xc42044c000)
-	parser/block.go:1226 +0x4f fp=0xc42049dc28 sp=0xc42049dc00 pc=0x1112cbf
-github.com/gomarkdown/markdown/parser.finalizeList(0xc42011c3f0)
-	parser/block.go:1226 +0x11a fp=0xc42049dcb8 sp=0xc42049dc28 pc=0x10febea
-github.com/gomarkdown/markdown/parser.(*Parser).list(0xc42045b200, 0x12e600e, 0x7, 0x1ffff2, 0x16, 0x0)
-	parser/block.go:1187 +0x27b fp=0xc42049dd30 sp=0xc42049dcb8 pc=0x10fe90b
-github.com/gomarkdown/markdown/parser.(*Parser).paragraph(0xc42045b200, 0x12e6000, 0x15, 0x200000, 0x0)
-	parser/block.go:1482 +0xfd4 fp=0xc42049de00 sp=0xc42049dd30 pc=0x11016d4
-github.com/gomarkdown/markdown/parser.(*Parser).block(0xc42045b200, 0x12e6000, 0x15, 0x200000)
-	parser/block.go:247 +0x6b8 fp=0xc42049de40 sp=0xc42049de00 pc=0x10f64e8
-github.com/gomarkdown/markdown/parser.(*Parser).Parse(0xc42045b200, 0x12e6000, 0x15, 0x200000, 0x8, 0x5a71671a)
-	parser/parser.go:241 +0x65 fp=0xc42049de78 sp=0xc42049de40 pc=0x110d295
-github.com/gomarkdown/markdown.Parse(0x12e6000, 0x15, 0x200000, 0x0, 0x1289f8c0, 0xa23912f)
-	markdown.go:46 +0x9a fp=0xc42049deb8 sp=0xc42049de78 pc=0x1118caa
-github.com/gomarkdown/markdown.Fuzz(0x12e6000, 0x15, 0x200000, 0x3)
-	fuzz.go:7 +0x60 fp=0xc42049def8 sp=0xc42049deb8 pc=0x1118bf0
-go-fuzz-dep.Main(0x11606d8)
-	/var/folders/v_/ksw1dqvd59v790zk2wqf_t_80000gn/T/go-fuzz-build351448921/goroot/src/go-fuzz-dep/main.go:49 +0xad fp=0xc42049df68 sp=0xc42049def8 pc=0x1065a4d
-main.main()
-	go.fuzz.main/main.go:10 +0x2d fp=0xc42049df80 sp=0xc42049df68 pc=0x1118dad
-runtime.main()
-*/
 func TestInfinite2(t *testing.T) {
 	test := ":\x00\x00\x00\x01V\n>* \x00\x80e\n\t* \n\n:\t"
-
-	c := make(chan bool, 1)
-	go func() {
-		Parse([]byte(test), nil)
-		c <- true
-	}()
-	select {
-	case <-c:
-	case <-time.After(2 * time.Second):
-		t.Fatalf("timed out")
-	}
+	parseWithShortTimeout(t, test)
+}
+
+func TestInfinite3(t *testing.T) {
+	test := "\xa2 \n\t: \n: "
+	parseWithShortTimeout(t, test)
 }

parser/block.go

@@ -1548,7 +1548,7 @@ func (p *Parser) paragraph(data []byte) int {
 		if p.extensions&DefinitionLists != 0 {
 			if p.dliPrefix(current) != 0 {
 				ret := p.list(data[prev:], ast.ListTypeDefinition)
-				return ret
+				return ret + prev
 			}
 		}