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Commitf342b71

Browse files
Prevent huge allocations when parsing goes wrong
There are no kind words to talk about how I feel aboutthe `debug/pe` package right now. What's very clear isthat it was never intended for arbitrary inputs.Anyway, these changes make us stray further from upstream,but when I look at upstream, I'm okay with it.
1 parent308c377 commitf342b71

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4 files changed

+33
-41
lines changed

4 files changed

+33
-41
lines changed

‎pe/file.go‎

Lines changed: 15 additions & 37 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,6 @@ import (
1010
"encoding/binary"
1111
"fmt"
1212
"io"
13-
"os"
1413

1514
"github.com/pkg/errors"
1615
)
@@ -30,33 +29,7 @@ type File struct {
3029
closer io.Closer
3130
readerAt io.ReaderAt
3231
baseint64
33-
}
34-
35-
// Open opens the named file using os.Open and prepares it for use as a PE binary.
36-
funcOpen(namestring) (*File,error) {
37-
f,err:=os.Open(name)
38-
iferr!=nil {
39-
returnnil,err
40-
}
41-
ff,err:=NewFile(f)
42-
iferr!=nil {
43-
f.Close()
44-
returnnil,err
45-
}
46-
ff.closer=f
47-
returnff,nil
48-
}
49-
50-
// Close closes the File.
51-
// If the File was created using NewFile directly instead of Open,
52-
// Close has no effect.
53-
func (f*File)Close()error {
54-
varerrerror
55-
iff.closer!=nil {
56-
err=f.closer.Close()
57-
f.closer=nil
58-
}
59-
returnerr
32+
sizeint64
6033
}
6134

6235
var (
@@ -67,10 +40,11 @@ var (
6740
// TODO(brainman): add Load function, as a replacement for NewFile, that does not call removeAuxSymbols (for performance)
6841

6942
// NewFile creates a new File for accessing a PE binary in an underlying reader.
70-
funcNewFile(r io.ReaderAt) (*File,error) {
43+
funcNewFile(r io.ReaderAt,sizeint64) (*File,error) {
7144
f:=new(File)
45+
f.size=size
7246
f.readerAt=r
73-
sr:=io.NewSectionReader(r,0,1<<63-1)
47+
sr:=io.NewSectionReader(r,0,size)
7448

7549
vardosheader [96]byte
7650
if_,err:=r.ReadAt(dosheader[0:],0);err!=nil {
@@ -80,16 +54,22 @@ func NewFile(r io.ReaderAt) (*File, error) {
8054
ifdosheader[0]=='M'&&dosheader[1]=='Z' {
8155
signoff:=int64(binary.LittleEndian.Uint32(dosheader[0x3c:]))
8256
varsign [4]byte
83-
r.ReadAt(sign[:],signoff)
57+
_,err:=r.ReadAt(sign[:],signoff)
58+
iferr!=nil {
59+
returnnil,err
60+
}
8461
if!(sign[0]=='P'&&sign[1]=='E'&&sign[2]==0&&sign[3]==0) {
8562
returnnil,fmt.Errorf("Invalid PE COFF file signature of %v.",sign)
8663
}
8764
base=signoff+4
8865
}else {
8966
base=int64(0)
9067
}
91-
sr.Seek(base,seekStart)
92-
iferr:=binary.Read(sr,binary.LittleEndian,&f.FileHeader);err!=nil {
68+
_,err:=sr.Seek(base,seekStart)
69+
iferr!=nil {
70+
returnnil,err
71+
}
72+
iferr=binary.Read(sr,binary.LittleEndian,&f.FileHeader);err!=nil {
9373
returnnil,err
9474
}
9575
switchf.FileHeader.Machine {
@@ -98,16 +78,14 @@ func NewFile(r io.ReaderAt) (*File, error) {
9878
returnnil,fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.",f.FileHeader.Machine)
9979
}
10080

101-
varerrerror
102-
10381
// Read string table.
104-
f.StringTable,err=readStringTable(&f.FileHeader,sr)
82+
f.StringTable,err=readStringTable(f,&f.FileHeader,sr)
10583
iferr!=nil {
10684
returnnil,err
10785
}
10886

10987
// Read symbol table.
110-
f.COFFSymbols,err=readCOFFSymbols(&f.FileHeader,sr)
88+
f.COFFSymbols,err=readCOFFSymbols(f,&f.FileHeader,sr)
11189
iferr!=nil {
11290
returnnil,err
11391
}

‎pe/string.go‎

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,8 @@ import (
88
"encoding/binary"
99
"fmt"
1010
"io"
11+
12+
"github.com/itchio/headway/united"
1113
)
1214

1315
// cstring converts ASCII byte sequence b to string.
@@ -22,13 +24,13 @@ func cstring(b []byte) string {
2224
// StringTable is a COFF string table.
2325
typeStringTable []byte
2426

25-
funcreadStringTable(fh*FileHeader,r io.ReadSeeker) (StringTable,error) {
27+
funcreadStringTable(f*File,fh*FileHeader,r io.ReadSeeker) (StringTable,error) {
2628
// COFF string table is located right after COFF symbol table.
2729
iffh.PointerToSymbolTable<=0 {
2830
returnnil,nil
2931
}
3032
offset:=fh.PointerToSymbolTable+COFFSymbolSize*fh.NumberOfSymbols
31-
_,err:=r.Seek(int64(offset),seekStart)
33+
_,err:=r.Seek(int64(offset),io.SeekStart)
3234
iferr!=nil {
3335
returnnil,fmt.Errorf("fail to seek to string table: %v",err)
3436
}
@@ -37,11 +39,18 @@ func readStringTable(fh *FileHeader, r io.ReadSeeker) (StringTable, error) {
3739
iferr!=nil {
3840
returnnil,fmt.Errorf("fail to read string table length: %v",err)
3941
}
42+
43+
varendint64=int64(offset)+int64(l)
44+
ifend>=f.size {
45+
returnnil,fmt.Errorf("debug/pe thinks the string table is at %s, but the file is only %s",united.FormatBytes(end),united.FormatBytes(f.size))
46+
}
47+
4048
// string table length includes itself
4149
ifl<=4 {
4250
returnnil,nil
4351
}
4452
l-=4
53+
4554
buf:=make([]byte,l)
4655
_,err=io.ReadFull(r,buf)
4756
iferr!=nil {

‎pe/symbol.go‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,7 +22,7 @@ type COFFSymbol struct {
2222
NumberOfAuxSymbolsuint8
2323
}
2424

25-
funcreadCOFFSymbols(fh*FileHeader,r io.ReadSeeker) ([]COFFSymbol,error) {
25+
funcreadCOFFSymbols(f*File,fh*FileHeader,r io.ReadSeeker) ([]COFFSymbol,error) {
2626
iffh.PointerToSymbolTable==0 {
2727
returnnil,nil
2828
}

‎probe.go‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -19,7 +19,12 @@ type ProbeParams struct {
1919
funcProbe(file eos.File,paramsProbeParams) (*PeInfo,error) {
2020
consumer:=params.Consumer
2121

22-
pf,err:=pe.NewFile(file)
22+
stats,err:=file.Stat()
23+
iferr!=nil {
24+
returnnil,errors.WithStack(err)
25+
}
26+
27+
pf,err:=pe.NewFile(file,stats.Size())
2328
iferr!=nil {
2429
returnnil,errors.WithStack(err)
2530
}

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