compress/gzip: fix stack exhaustion bug in Reader.Read
Replace recursion with iteration in Reader.Read to avoid stack
exhaustion when there are a large number of files.
Fixes CVE-2022-30631
Fixes #53168
Change-Id: I47d8afe3f2d40b0213ab61431df9b221794dbfe0
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1455673
Reviewed-by: Roland Shoemaker <bracewell@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/417067
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/src/compress/gzip/gunzip.go b/src/compress/gzip/gunzip.go
index aa6780f..ba8de97 100644
--- a/src/compress/gzip/gunzip.go
+++ b/src/compress/gzip/gunzip.go
@@ -248,42 +248,40 @@
return 0, z.err
}
- n, z.err = z.decompressor.Read(p)
- z.digest = crc32.Update(z.digest, crc32.IEEETable, p[:n])
- z.size += uint32(n)
- if z.err != io.EOF {
- // In the normal case we return here.
- return n, z.err
+ for n == 0 {
+ n, z.err = z.decompressor.Read(p)
+ z.digest = crc32.Update(z.digest, crc32.IEEETable, p[:n])
+ z.size += uint32(n)
+ if z.err != io.EOF {
+ // In the normal case we return here.
+ return n, z.err
+ }
+
+ // Finished file; check checksum and size.
+ if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil {
+ z.err = noEOF(err)
+ return n, z.err
+ }
+ digest := le.Uint32(z.buf[:4])
+ size := le.Uint32(z.buf[4:8])
+ if digest != z.digest || size != z.size {
+ z.err = ErrChecksum
+ return n, z.err
+ }
+ z.digest, z.size = 0, 0
+
+ // File is ok; check if there is another.
+ if !z.multistream {
+ return n, io.EOF
+ }
+ z.err = nil // Remove io.EOF
+
+ if _, z.err = z.readHeader(); z.err != nil {
+ return n, z.err
+ }
}
- // Finished file; check checksum and size.
- if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil {
- z.err = noEOF(err)
- return n, z.err
- }
- digest := le.Uint32(z.buf[:4])
- size := le.Uint32(z.buf[4:8])
- if digest != z.digest || size != z.size {
- z.err = ErrChecksum
- return n, z.err
- }
- z.digest, z.size = 0, 0
-
- // File is ok; check if there is another.
- if !z.multistream {
- return n, io.EOF
- }
- z.err = nil // Remove io.EOF
-
- if _, z.err = z.readHeader(); z.err != nil {
- return n, z.err
- }
-
- // Read from next file, if necessary.
- if n > 0 {
- return n, nil
- }
- return z.Read(p)
+ return n, nil
}
// Close closes the Reader. It does not close the underlying io.Reader.
diff --git a/src/compress/gzip/gunzip_test.go b/src/compress/gzip/gunzip_test.go
index be69185..3309ff6 100644
--- a/src/compress/gzip/gunzip_test.go
+++ b/src/compress/gzip/gunzip_test.go
@@ -569,3 +569,19 @@
}
}
}
+
+func TestCVE202230631(t *testing.T) {
+ var empty = []byte{0x1f, 0x8b, 0x08, 0x00, 0xa7, 0x8f, 0x43, 0x62, 0x00,
+ 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
+ r := bytes.NewReader(bytes.Repeat(empty, 4e6))
+ z, err := NewReader(r)
+ if err != nil {
+ t.Fatalf("NewReader: got %v, want nil", err)
+ }
+ // Prior to CVE-2022-30631 fix, this would cause an unrecoverable panic due
+ // to stack exhaustion.
+ _, err = z.Read(make([]byte, 10))
+ if err != io.EOF {
+ t.Errorf("Reader.Read: got %v, want %v", err, io.EOF)
+ }
+}
