Backport fix for CVE-2023-45290

patches/004-net-textproto-mime-multipart-a.patch

@@ -0,0 +1,266 @@
+From c911efa18163bea9ef152be227b07c5cac0e449d Mon Sep 17 00:00:00 2001
+From: Damien Neil <[email protected]>
+Date: Tue, 16 Jan 2024 15:37:52 -0800
+Subject: [PATCH] [release-branch.go1.21] net/textproto, mime/multipart: avoid
+ unbounded read in MIME header
+
+mime/multipart.Reader.ReadForm allows specifying the maximum amount
+of memory that will be consumed by the form. While this limit is
+correctly applied to the parsed form data structure, it was not
+being applied to individual header lines in a form.
+
+For example, when presented with a form containing a header line
+that never ends, ReadForm will continue to read the line until it
+runs out of memory.
+
+Limit the amount of data consumed when reading a header.
+
+Fixes CVE-2023-45290
+Fixes #65389
+For #65383
+
+Change-Id: I7f9264d25752009e95f6b2c80e3d76aaf321d658
+Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/2134435
+Reviewed-by: Roland Shoemaker <[email protected]>
+Reviewed-by: Tatiana Bradley <[email protected]>
+Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/2173776
+Reviewed-by: Carlos Amedee <[email protected]>
+Reviewed-on: https://go-review.googlesource.com/c/go/+/569240
+Auto-Submit: Michael Knyszek <[email protected]>
+LUCI-TryBot-Result: Go LUCI <[email protected]>
+Reviewed-by: Carlos Amedee <[email protected]>
+---
+ src/mime/multipart/formdata_test.go | 42 +++++++++++++++++++++++++
+ src/net/textproto/reader.go         | 48 ++++++++++++++++++++---------
+ src/net/textproto/reader_test.go    | 12 ++++++++
+ 3 files changed, 87 insertions(+), 15 deletions(-)
+
+diff --git a/src/mime/multipart/formdata_test.go b/src/mime/multipart/formdata_test.go
+index a618a64beb..dd44ae4e21 100644
+--- a/src/mime/multipart/formdata_test.go
++++ b/src/mime/multipart/formdata_test.go
+@@ -421,6 +421,48 @@ func TestReadFormLimits(t *testing.T) {
+ 	}
+ }
+
++func TestReadFormEndlessHeaderLine(t *testing.T) {
++	for _, test := range []struct {
++		name   string
++		prefix string
++	}{{
++		name:   "name",
++		prefix: "X-",
++	}, {
++		name:   "value",
++		prefix: "X-Header: ",
++	}, {
++		name:   "continuation",
++		prefix: "X-Header: foo\r\n  ",
++	}} {
++		t.Run(test.name, func(t *testing.T) {
++			const eol = "\r\n"
++			s := `--boundary` + eol
++			s += `Content-Disposition: form-data; name="a"` + eol
++			s += `Content-Type: text/plain` + eol
++			s += test.prefix
++			fr := io.MultiReader(
++				strings.NewReader(s),
++				neverendingReader('X'),
++			)
++			r := NewReader(fr, "boundary")
++			_, err := r.ReadForm(1 << 20)
++			if err != ErrMessageTooLarge {
++				t.Fatalf("ReadForm(1 << 20): %v, want ErrMessageTooLarge", err)
++			}
++		})
++	}
++}
++
++type neverendingReader byte
++
++func (r neverendingReader) Read(p []byte) (n int, err error) {
++	for i := range p {
++		p[i] = byte(r)
++	}
++	return len(p), nil
++}
++
+ func BenchmarkReadForm(b *testing.B) {
+ 	for _, test := range []struct {
+ 		name string
+diff --git a/src/net/textproto/reader.go b/src/net/textproto/reader.go
+index fc2590b1cd..fcd1a011ac 100644
+--- a/src/net/textproto/reader.go
++++ b/src/net/textproto/reader.go
+@@ -16,6 +16,10 @@ import (
+ 	"sync"
+ )
+
++// TODO: This should be a distinguishable error (ErrMessageTooLarge)
++// to allow mime/multipart to detect it.
++var errMessageTooLarge = errors.New("message too large")
++
+ // A Reader implements convenience methods for reading requests
+ // or responses from a text protocol network connection.
+ type Reader struct {
+@@ -36,20 +40,23 @@ func NewReader(r *bufio.Reader) *Reader {
+ // ReadLine reads a single line from r,
+ // eliding the final \n or \r\n from the returned string.
+ func (r *Reader) ReadLine() (string, error) {
+-	line, err := r.readLineSlice()
++	line, err := r.readLineSlice(-1)
+ 	return string(line), err
+ }
+
+ // ReadLineBytes is like ReadLine but returns a []byte instead of a string.
+ func (r *Reader) ReadLineBytes() ([]byte, error) {
+-	line, err := r.readLineSlice()
++	line, err := r.readLineSlice(-1)
+ 	if line != nil {
+ 		line = bytes.Clone(line)
+ 	}
+ 	return line, err
+ }
+
+-func (r *Reader) readLineSlice() ([]byte, error) {
++// readLineSlice reads a single line from r,
++// up to lim bytes long (or unlimited if lim is less than 0),
++// eliding the final \r or \r\n from the returned string.
++func (r *Reader) readLineSlice(lim int64) ([]byte, error) {
+ 	r.closeDot()
+ 	var line []byte
+ 	for {
+@@ -57,6 +64,9 @@ func (r *Reader) readLineSlice() ([]byte, error) {
+ 		if err != nil {
+ 			return nil, err
+ 		}
++		if lim >= 0 && int64(len(line))+int64(len(l)) > lim {
++			return nil, errMessageTooLarge
++		}
+ 		// Avoid the copy if the first call produced a full line.
+ 		if line == nil && !more {
+ 			return l, nil
+@@ -88,7 +98,7 @@ func (r *Reader) readLineSlice() ([]byte, error) {
+ //
+ // Empty lines are never continued.
+ func (r *Reader) ReadContinuedLine() (string, error) {
+-	line, err := r.readContinuedLineSlice(noValidation)
++	line, err := r.readContinuedLineSlice(-1, noValidation)
+ 	return string(line), err
+ }
+
+@@ -109,7 +119,7 @@ func trim(s []byte) []byte {
+ // ReadContinuedLineBytes is like ReadContinuedLine but
+ // returns a []byte instead of a string.
+ func (r *Reader) ReadContinuedLineBytes() ([]byte, error) {
+-	line, err := r.readContinuedLineSlice(noValidation)
++	line, err := r.readContinuedLineSlice(-1, noValidation)
+ 	if line != nil {
+ 		line = bytes.Clone(line)
+ 	}
+@@ -120,13 +130,14 @@ func (r *Reader) ReadContinuedLineBytes() ([]byte, error) {
+ // returning a byte slice with all lines. The validateFirstLine function
+ // is run on the first read line, and if it returns an error then this
+ // error is returned from readContinuedLineSlice.
+-func (r *Reader) readContinuedLineSlice(validateFirstLine func([]byte) error) ([]byte, error) {
++// It reads up to lim bytes of data (or unlimited if lim is less than 0).
++func (r *Reader) readContinuedLineSlice(lim int64, validateFirstLine func([]byte) error) ([]byte, error) {
+ 	if validateFirstLine == nil {
+ 		return nil, fmt.Errorf("missing validateFirstLine func")
+ 	}
+
+ 	// Read the first line.
+-	line, err := r.readLineSlice()
++	line, err := r.readLineSlice(lim)
+ 	if err != nil {
+ 		return nil, err
+ 	}
+@@ -154,13 +165,21 @@ func (r *Reader) readContinuedLineSlice(validateFirstLine func([]byte) error) ([
+ 	// copy the slice into buf.
+ 	r.buf = append(r.buf[:0], trim(line)...)
+
++	if lim < 0 {
++		lim = math.MaxInt64
++	}
++	lim -= int64(len(r.buf))
++
+ 	// Read continuation lines.
+ 	for r.skipSpace() > 0 {
+-		line, err := r.readLineSlice()
++		r.buf = append(r.buf, ' ')
++		if int64(len(r.buf)) >= lim {
++			return nil, errMessageTooLarge
++		}
++		line, err := r.readLineSlice(lim - int64(len(r.buf)))
+ 		if err != nil {
+ 			break
+ 		}
+-		r.buf = append(r.buf, ' ')
+ 		r.buf = append(r.buf, trim(line)...)
+ 	}
+ 	return r.buf, nil
+@@ -507,7 +526,8 @@ func readMIMEHeader(r *Reader, maxMemory, maxHeaders int64) (MIMEHeader, error)
+
+ 	// The first line cannot start with a leading space.
+ 	if buf, err := r.R.Peek(1); err == nil && (buf[0] == ' ' || buf[0] == '\t') {
+-		line, err := r.readLineSlice()
++		const errorLimit = 80 // arbitrary limit on how much of the line we'll quote
++		line, err := r.readLineSlice(errorLimit)
+ 		if err != nil {
+ 			return m, err
+ 		}
+@@ -515,7 +535,7 @@ func readMIMEHeader(r *Reader, maxMemory, maxHeaders int64) (MIMEHeader, error)
+ 	}
+
+ 	for {
+-		kv, err := r.readContinuedLineSlice(mustHaveFieldNameColon)
++		kv, err := r.readContinuedLineSlice(maxMemory, mustHaveFieldNameColon)
+ 		if len(kv) == 0 {
+ 			return m, err
+ 		}
+@@ -544,7 +564,7 @@ func readMIMEHeader(r *Reader, maxMemory, maxHeaders int64) (MIMEHeader, error)
+
+ 		maxHeaders--
+ 		if maxHeaders < 0 {
+-			return nil, errors.New("message too large")
++			return nil, errMessageTooLarge
+ 		}
+
+ 		// Skip initial spaces in value.
+@@ -557,9 +577,7 @@ func readMIMEHeader(r *Reader, maxMemory, maxHeaders int64) (MIMEHeader, error)
+ 		}
+ 		maxMemory -= int64(len(value))
+ 		if maxMemory < 0 {
+-			// TODO: This should be a distinguishable error (ErrMessageTooLarge)
+-			// to allow mime/multipart to detect it.
+-			return m, errors.New("message too large")
++			return m, errMessageTooLarge
+ 		}
+ 		if vv == nil && len(strs) > 0 {
+ 			// More than likely this will be a single-element key.
+diff --git a/src/net/textproto/reader_test.go b/src/net/textproto/reader_test.go
+index 696ae406f3..26ff617470 100644
+--- a/src/net/textproto/reader_test.go
++++ b/src/net/textproto/reader_test.go
+@@ -36,6 +36,18 @@ func TestReadLine(t *testing.T) {
+ 	}
+ }
+
++func TestReadLineLongLine(t *testing.T) {
++	line := strings.Repeat("12345", 10000)
++	r := reader(line + "\r\n")
++	s, err := r.ReadLine()
++	if err != nil {
++		t.Fatalf("Line 1: %v", err)
++	}
++	if s != line {
++		t.Fatalf("%v-byte line does not match expected %v-byte line", len(s), len(line))
++	}
++}
++
+ func TestReadContinuedLine(t *testing.T) {
+ 	r := reader("line1\nline\n 2\nline3\n")
+ 	s, err := r.ReadContinuedLine()
+-- 
+2.45.1
+