[release-branch.go1.20] go/scanner: reject large line and column numbers in //line...

Setting a large line or column number using a //line directive can cause
integer overflow even in small source files.

Limit line and column numbers in //line directives to 2^30-1, which
is small enough to avoid int32 overflow on all reasonbly-sized files.

Fixes CVE-2023-24537
For #59180
Fixes #59274

Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1802456
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-by: Roland Shoemaker <bracewell@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
Change-Id: Ib9c5cb38428ed34ab129d451b00a2998e72c861c
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1802401
TryBot-Result: Security TryBots <security-trybots@go-security-trybots.iam.gserviceaccount.com>
Run-TryBot: Roland Shoemaker <bracewell@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/481992
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Bypass: Michael Knyszek <mknyszek@google.com>

diff --git a/src/go/parser/parser_test.go b/src/go/parser/parser_test.go
index 153562df75068de8f5ddee0a2f4fb946fded1510..22b11a0cc453548e37aeee0bd90ec5f2dcfd1f4b 100644 (file)
--- a/src/go/parser/parser_test.go
+++ b/src/go/parser/parser_test.go
@@ -764,3 +764,19 @@ func TestRangePos(t *testing.T) {
                })
        }
 }
+
+// TestIssue59180 tests that line number overflow doesn't cause an infinite loop.
+func TestIssue59180(t *testing.T) {
+       testcases := []string{
+               "package p\n//line :9223372036854775806\n\n//",
+               "package p\n//line :1:9223372036854775806\n\n//",
+               "package p\n//line file:9223372036854775806\n\n//",
+       }
+
+       for _, src := range testcases {
+               _, err := ParseFile(token.NewFileSet(), "", src, ParseComments)
+               if err == nil {
+                       t.Errorf("ParseFile(%s) succeeded unexpectedly", src)
+               }
+       }
+}

diff --git a/src/go/scanner/scanner.go b/src/go/scanner/scanner.go
index 16958d22ce2997b4197ef14c0c095b9389d687fa..0cd9f5901d0bbae277e44ab79a8975ec86c62418 100644 (file)
--- a/src/go/scanner/scanner.go
+++ b/src/go/scanner/scanner.go
@@ -253,13 +253,16 @@ func (s *Scanner) updateLineInfo(next, offs int, text []byte) {
                return
        }
 
+       // Put a cap on the maximum size of line and column numbers.
+       // 30 bits allows for some additional space before wrapping an int32.
+       const maxLineCol = 1<<30 - 1
        var line, col int
        i2, n2, ok2 := trailingDigits(text[:i-1])
        if ok2 {
                //line filename:line:col
                i, i2 = i2, i
                line, col = n2, n
-               if col == 0 {
+               if col == 0 || col > maxLineCol {
                        s.error(offs+i2, "invalid column number: "+string(text[i2:]))
                        return
                }
@@ -269,7 +272,7 @@ func (s *Scanner) updateLineInfo(next, offs int, text []byte) {
                line = n
        }
 
-       if line == 0 {
+       if line == 0 || line > maxLineCol {
                s.error(offs+i, "invalid line number: "+string(text[i:]))
                return
        }