From b65dd43c5bb519de311f5428308bbc681d62402b Mon Sep 17 00:00:00 2001
From: Sunny Klair <sunny.basi@gmail.com>
Date: Thu, 26 Oct 2017 15:34:31 -0400
Subject: [PATCH] Validate index series/postings/symbol table checksums on read

---
 index.go | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/index.go b/index.go
index cc0ad140c4..4d046de992 100644
--- a/index.go
+++ b/index.go
@@ -626,7 +626,7 @@ func (r *indexReader) readTOC() error {
 	r.toc.postings = d.be64()
 	r.toc.postingsTable = d.be64()
 
-	if valid, err := r.validCrc(d.be32(), len(r.b)-indexTOCLen, indexTOCLen-4); !valid {
+	if valid, err := r.checkCrc(d.be32(), len(r.b)-indexTOCLen, indexTOCLen-4); !valid {
 		return errors.Wrap(err, "TOC checksum")
 	}
 
@@ -640,7 +640,7 @@ func (r *indexReader) decbufAt(off int) decbuf {
 	return decbuf{b: r.b[off:]}
 }
 
-func (r *indexReader) validCrc(crc uint32, off, cnt int) (bool, error) {
+func (r *indexReader) checkCrc(crc uint32, off, cnt int) (bool, error) {
 	c2 := newCRC32()
 	if len(r.b) < off+cnt {
 		return false, errInvalidSize
@@ -663,7 +663,8 @@ func (r *indexReader) readSymbols(off int) error {
 	}
 	var (
 		d1      = r.decbufAt(int(off))
-		d2      = d1.decbuf(d1.be32int())
+		l       = d1.be32int()
+		d2      = d1.decbuf(l)
 		origLen = d2.len()
 		cnt     = d2.be32int()
 		basePos = uint32(off) + 4
@@ -676,6 +677,9 @@ func (r *indexReader) readSymbols(off int) error {
 		nextPos = basePos + uint32(origLen-d2.len())
 		cnt--
 	}
+	if valid, err := r.checkCrc(d1.be32(), int(off)+4, l); !valid {
+		return errors.Wrap(err, "symbol table checksum")
+	}
 	return d2.err()
 }
 
@@ -685,10 +689,10 @@ func (r *indexReader) readOffsetTable(off uint64) (map[string]uint32, error) {
 	const sep = "\xff"
 
 	var (
-		d1       = r.decbufAt(int(off))
-		tableLen = d1.be32int()
-		d2       = d1.decbuf(tableLen)
-		cnt      = d2.be32()
+		d1  = r.decbufAt(int(off))
+		l   = d1.be32int()
+		d2  = d1.decbuf(l)
+		cnt = d2.be32()
 	)
 
 	res := make(map[string]uint32, 512)
@@ -705,7 +709,7 @@ func (r *indexReader) readOffsetTable(off uint64) (map[string]uint32, error) {
 		cnt--
 	}
 
-	if valid, err := r.validCrc(d1.be32(), int(off)+4, tableLen); !valid {
+	if valid, err := r.checkCrc(d1.be32(), int(off)+4, l); !valid {
 		return res, errors.Wrap(err, "offset table checksum")
 	}
 
@@ -765,7 +769,8 @@ func (r *indexReader) LabelValues(names ...string) (StringTuples, error) {
 	}
 
 	d1 := r.decbufAt(int(off))
-	d2 := d1.decbuf(d1.be32int())
+	l := d1.be32int()
+	d2 := d1.decbuf(l)
 
 	nc := d2.be32int()
 	d2.be32() // consume unused value entry count.
@@ -774,7 +779,9 @@ func (r *indexReader) LabelValues(names ...string) (StringTuples, error) {
 		return nil, errors.Wrap(d2.err(), "read label value index")
 	}
 
-	// TODO(fabxc): verify checksum in 4 remaining bytes of d1.
+	if valid, err := r.checkCrc(d1.be32(), int(off)+4, l); !valid {
+		return nil, errors.Wrap(err, "read label values checksum")
+	}
 
 	st := &serializedStringTuples{
 		l:      nc,
@@ -802,7 +809,9 @@ func (r *indexReader) LabelIndices() ([][]string, error) {
 
 func (r *indexReader) Series(ref uint64, lbls *labels.Labels, chks *[]ChunkMeta) error {
 	d1 := r.decbufAt(int(ref))
-	d2 := d1.decbuf(int(d1.uvarint()))
+	l := d1.uvarint()
+	sl := len(r.b[ref:]) - d1.len() // # bytes in l
+	d2 := d1.decbuf(l)
 
 	*lbls = (*lbls)[:0]
 	*chks = (*chks)[:0]
@@ -865,7 +874,9 @@ func (r *indexReader) Series(ref uint64, lbls *labels.Labels, chks *[]ChunkMeta)
 		})
 	}
 
-	// TODO(fabxc): verify CRC32.
+	if valid, err := r.checkCrc(d1.be32(), int(ref)+sl, l); !valid {
+		return errors.Wrap(err, "series checksum")
+	}
 
 	return nil
 }
@@ -880,7 +891,8 @@ func (r *indexReader) Postings(name, value string) (Postings, error) {
 	}
 
 	d1 := r.decbufAt(int(off))
-	d2 := d1.decbuf(d1.be32int())
+	l := d1.be32int()
+	d2 := d1.decbuf(l)
 
 	d2.be32() // consume unused postings list length.
 
@@ -888,7 +900,9 @@ func (r *indexReader) Postings(name, value string) (Postings, error) {
 		return nil, errors.Wrap(d2.err(), "get postings bytes")
 	}
 
-	// TODO(fabxc): read checksum from 4 remainer bytes of d1 and verify.
+	if valid, err := r.checkCrc(d1.be32(), int(off)+4, l); !valid {
+		return nil, errors.Wrap(err, "postings checksum")
+	}
 
 	return newBigEndianPostings(d2.get()), nil
 }