mirrors/tar-split
1
0
Fork 1
mirror of https://github.com/vbatts/tar-split.git synced 2025-07-03 14:58:30 +00:00
Code Releases Activity

archive/tar: fix numeric overflow issues in readGNUSparseMap0x1

Browse source 
Motivation:
* The logic to verify the numEntries can overflow and incorrectly
pass, allowing a malicious file to allocate arbitrary memory.
* The use of strconv.ParseInt does not set the integer precision
to 64bit, causing this code to work incorrectly on 32bit machines.

Change-Id: I1b1571a750a84f2dde97cc329ed04fe2342aaa60
Reviewed-on: https://go-review.googlesource.com/15173
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Joe Tsai 2015-10-01 01:04:24 -07:00 • committed by Vincent Batts
parent cb423795eb
commit cf83c95de8
2 changed files with 173 additions and 40 deletions
Download patch file Download diff file Expand all files Collapse all files

57
archive/tar/reader.go
View file

@ -504,20 +504,48 @@ func (tr *Reader) octal(b []byte) int64 {
return int64(x)
}
// skipUnread skips any unread bytes in the existing file entry, as well as any alignment padding.
func (tr *Reader) skipUnread() {
nr := tr.numBytes() + tr.pad // number of bytes to skip
// skipUnread skips any unread bytes in the existing file entry, as well as any
// alignment padding. It returns io.ErrUnexpectedEOF if any io.EOF is
// encountered in the data portion; it is okay to hit io.EOF in the padding.
//
// Note that this function still works properly even when sparse files are being
// used since numBytes returns the bytes remaining in the underlying io.Reader.
func (tr *Reader) skipUnread() error {
dataSkip := tr.numBytes() // Number of data bytes to skip
totalSkip := dataSkip + tr.pad // Total number of bytes to skip
tr.curr, tr.pad = nil, 0
if tr.RawAccounting {
_, tr.err = io.CopyN(tr.rawBytes, tr.r, nr)
return
_, tr.err = io.CopyN(tr.rawBytes, tr.r, totalSkip)
return tr.err
}
if sr, ok := tr.r.(io.Seeker); ok {
if _, err := sr.Seek(nr, os.SEEK_CUR); err == nil {
return
// If possible, Seek to the last byte before the end of the data section.
// Do this because Seek is often lazy about reporting errors; this will mask
// the fact that the tar stream may be truncated. We can rely on the
// io.CopyN done shortly afterwards to trigger any IO errors.
var seekSkipped int64 // Number of bytes skipped via Seek
if sr, ok := tr.r.(io.Seeker); ok && dataSkip > 1 {
// Not all io.Seeker can actually Seek. For example, os.Stdin implements
// io.Seeker, but calling Seek always returns an error and performs
// no action. Thus, we try an innocent seek to the current position
// to see if Seek is really supported.
pos1, err := sr.Seek(0, os.SEEK_CUR)
if err == nil {
// Seek seems supported, so perform the real Seek.
pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR)
if err != nil {
tr.err = err
return tr.err
}
seekSkipped = pos2 - pos1
}
}
_, tr.err = io.CopyN(ioutil.Discard, tr.r, nr)
var copySkipped int64 // Number of bytes skipped via CopyN
copySkipped, tr.err = io.CopyN(ioutil.Discard, tr.r, totalSkip-seekSkipped)
if tr.err == io.EOF && seekSkipped+copySkipped < dataSkip {
tr.err = io.ErrUnexpectedEOF
}
return tr.err
}
func (tr *Reader) verifyChecksum(header []byte) bool {
@ -530,6 +558,13 @@ func (tr *Reader) verifyChecksum(header []byte) bool {
return given == unsigned || given == signed
}
// readHeader reads the next block header and assumes that the underlying reader
// is already aligned to a block boundary.
//
// The err will be set to io.EOF only when one of the following occurs:
// * Exactly 0 bytes are read and EOF is hit.
// * Exactly 1 block of zeros is read and EOF is hit.
// * At least 2 blocks of zeros are read.
func (tr *Reader) readHeader() *Header {
header := tr.hdrBuff[:]
copy(header, zeroBlock)
@ -541,7 +576,7 @@ func (tr *Reader) readHeader() *Header {
return nil
}
}
return nil
return nil // io.EOF is okay here
}
if tr.RawAccounting {
if _, tr.err = tr.rawBytes.Write(header); tr.err != nil {
@ -558,7 +593,7 @@ func (tr *Reader) readHeader() *Header {
return nil
}
}
return nil
return nil // io.EOF is okay here
}
if tr.RawAccounting {
if _, tr.err = tr.rawBytes.Write(header); tr.err != nil {