Enforce integer limits of the Postgres wire protocol

buf.go

@@ -3,6 +3,7 @@ package pq
 import (
 	"bytes"
 	"encoding/binary"
+	"math"
 
 	"github.com/lib/pq/oid"
 )
@@ -79,12 +80,18 @@ func (b *writeBuf) bytes(v []byte) {
 
 func (b *writeBuf) wrap() []byte {
 	p := b.buf[b.pos:]
+	if len(p) > math.MaxUint32 {
+		panic("message too large")
+	}
 	binary.BigEndian.PutUint32(p, uint32(len(p)))
 	return b.buf
 }
 
 func (b *writeBuf) next(c byte) {
 	p := b.buf[b.pos:]
+	if len(p) > math.MaxUint32 {
+		panic("message too large")
+	}
 	binary.BigEndian.PutUint32(p, uint32(len(p)))
 	b.pos = len(b.buf) + 1
 	b.buf = append(b.buf, c, 0, 0, 0, 0)

conn.go

@@ -12,6 +12,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math"
 	"net"
 	"os"
 	"os/user"
@@ -820,6 +821,9 @@ func decideColumnFormats(
 		return colFmts, colFmtDataAllText
 	} else {
 		colFmtData = make([]byte, 2+len(colFmts)*2)
+		if len(colFmts) > math.MaxUint16 {
+			panic("too many columns")
+		}
 		binary.BigEndian.PutUint16(colFmtData, uint16(len(colFmts)))
 		for i, v := range colFmts {
 			binary.BigEndian.PutUint16(colFmtData[2+i*2:], uint16(v))

copy.go

@@ -7,6 +7,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"math"
 	"sync"
 )
 
@@ -140,6 +141,9 @@ awaitCopyInResponse:
 }
 
 func (ci *copyin) flush(buf []byte) {
+	if len(buf)-1 > math.MaxUint32 {
+		panic("too many columns")
+	}
 	// set message length (without message identifier)
 	binary.BigEndian.PutUint32(buf[1:], uint32(len(buf)-1))