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Validate index offset table checksums on read

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This commit is contained in:
Sunny Klair 2017-10-26 13:48:31 -04:00
parent 4fdf9b195c
commit ab02ea4de4
1 changed files with 24 additions and 12 deletions
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36
index.go
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@ -619,11 +619,6 @@ func newIndexReader(dir string) (*indexReader, error) {
func (r *indexReader) readTOC() error {
d := r.decbufAt(len(r.b) - indexTOCLen)
crc := newCRC32()
if _, err := crc.Write(d.get()[:d.len()-4]); err != nil {
return errors.Wrap(err, "write to hash")
}
r.toc.symbols = d.be64()
r.toc.series = d.be64()
r.toc.labelIndices = d.be64()
@ -631,9 +626,8 @@ func (r *indexReader) readTOC() error {
r.toc.postings = d.be64()
r.toc.postingsTable = d.be64()
// Validate checksum
if d.be32() != crc.Sum32() {
return errors.Wrap(errInvalidChecksum, "TOC checksum")
if valid, err := r.validCrc(d.be32(), len(r.b)-indexTOCLen, indexTOCLen-4); !valid {
return errors.Wrap(err, "TOC checksum")
}
return d.err()
@ -646,6 +640,20 @@ func (r *indexReader) decbufAt(off int) decbuf {
return decbuf{b: r.b[off:]}
}
func (r *indexReader) validCrc(crc uint32, off, cnt int) (bool, error) {
c2 := newCRC32()
if len(r.b) < off+cnt {
return false, errInvalidSize
}
if _, err := c2.Write(r.b[off : off+cnt]); err != nil {
return false, errors.Wrap(err, "write to hash")
}
if c2.Sum32() != crc {
return false, errInvalidChecksum
}
return true, nil
}
// readSymbols reads the symbol table fully into memory and allocates proper strings for them.
// Strings backed by the mmap'd memory would cause memory faults if applications keep using them
// after the reader is closed.
@ -677,9 +685,10 @@ func (r *indexReader) readOffsetTable(off uint64) (map[string]uint32, error) {
const sep = "\xff"
var (
d1 = r.decbufAt(int(off))
d2 = d1.decbuf(d1.be32int())
cnt = d2.be32()
d1 = r.decbufAt(int(off))
tableLen = d1.be32int()
d2 = d1.decbuf(tableLen)
cnt = d2.be32()
)
res := make(map[string]uint32, 512)
@ -696,7 +705,10 @@ func (r *indexReader) readOffsetTable(off uint64) (map[string]uint32, error) {
cnt--
}
// TODO(fabxc): verify checksum from remainer of d1.
if valid, err := r.validCrc(d1.be32(), int(off)+4, tableLen); !valid {
return res, errors.Wrap(err, "offset table checksum")
}
return res, d2.err()
}