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authorAntonio Jesus Navarro Perez <antnavper@gmail.com>2017-07-19 15:21:49 +0200
committerAntonio Jesus Navarro Perez <antnavper@gmail.com>2017-07-19 15:21:49 +0200
commit4f713d10b2c6c182ab853184f7469912e9c85c92 (patch)
treeba2a569f49d6c7797e3072afc7bb3a3abe37159f /plumbing/format/packfile/patch_delta.go
parent9775f829d6fb8026a2d73af89896a8f2cc5f7c50 (diff)
downloadgo-git-4f713d10b2c6c182ab853184f7469912e9c85c92.tar.gz
packfile: Avoid panics patching corrupted deltas
Diffstat (limited to 'plumbing/format/packfile/patch_delta.go')
-rw-r--r--plumbing/format/packfile/patch_delta.go77
1 files changed, 64 insertions, 13 deletions
diff --git a/plumbing/format/packfile/patch_delta.go b/plumbing/format/packfile/patch_delta.go
index 840f840..976cabc 100644
--- a/plumbing/format/packfile/patch_delta.go
+++ b/plumbing/format/packfile/patch_delta.go
@@ -1,6 +1,7 @@
package packfile
import (
+ "errors"
"io/ioutil"
"gopkg.in/src-d/go-git.v4/plumbing"
@@ -30,7 +31,11 @@ func ApplyDelta(target, base plumbing.EncodedObject, delta []byte) error {
return err
}
- dst := PatchDelta(src, delta)
+ dst, err := PatchDelta(src, delta)
+ if err != nil {
+ return err
+ }
+
target.SetSize(int64(len(dst)))
if _, err := w.Write(dst); err != nil {
@@ -40,15 +45,22 @@ func ApplyDelta(target, base plumbing.EncodedObject, delta []byte) error {
return nil
}
+var (
+ ErrInvalidDelta = errors.New("invalid delta")
+ ErrDeltaCmd = errors.New("wrong delta command")
+)
+
// PatchDelta returns the result of applying the modification deltas in delta to src.
-func PatchDelta(src, delta []byte) []byte {
+// An error will be returned if delta is corrupted (ErrDeltaLen) or an action command
+// is not copy from source or copy from delta (ErrDeltaCmd).
+func PatchDelta(src, delta []byte) ([]byte, error) {
if len(delta) < deltaSizeMin {
- return nil
+ return nil, ErrInvalidDelta
}
srcSz, delta := decodeLEB128(delta)
if srcSz != uint(len(src)) {
- return nil
+ return nil, ErrInvalidDelta
}
targetSz, delta := decodeLEB128(delta)
@@ -57,12 +69,25 @@ func PatchDelta(src, delta []byte) []byte {
var dest []byte
var cmd byte
for {
+ if len(delta) == 0 {
+ return nil, ErrInvalidDelta
+ }
+
cmd = delta[0]
delta = delta[1:]
if isCopyFromSrc(cmd) {
var offset, sz uint
- offset, delta = decodeOffset(cmd, delta)
- sz, delta = decodeSize(cmd, delta)
+ var err error
+ offset, delta, err = decodeOffset(cmd, delta)
+ if err != nil {
+ return nil, err
+ }
+
+ sz, delta, err = decodeSize(cmd, delta)
+ if err != nil {
+ return nil, err
+ }
+
if invalidSize(sz, targetSz) ||
invalidOffsetSize(offset, sz, srcSz) {
break
@@ -72,13 +97,18 @@ func PatchDelta(src, delta []byte) []byte {
} else if isCopyFromDelta(cmd) {
sz := uint(cmd) // cmd is the size itself
if invalidSize(sz, targetSz) {
- break
+ return nil, ErrInvalidDelta
+ }
+
+ if uint(len(delta)) < sz {
+ return nil, ErrInvalidDelta
}
+
dest = append(dest, delta[0:sz]...)
remainingTargetSz -= sz
delta = delta[sz:]
} else {
- return nil
+ return nil, ErrDeltaCmd
}
if remainingTargetSz <= 0 {
@@ -86,7 +116,7 @@ func PatchDelta(src, delta []byte) []byte {
}
}
- return dest
+ return dest, nil
}
// Decodes a number encoded as an unsigned LEB128 at the start of some
@@ -124,39 +154,60 @@ func isCopyFromDelta(cmd byte) bool {
return (cmd&0x80) == 0 && cmd != 0
}
-func decodeOffset(cmd byte, delta []byte) (uint, []byte) {
+func decodeOffset(cmd byte, delta []byte) (uint, []byte, error) {
var offset uint
if (cmd & 0x01) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
offset = uint(delta[0])
delta = delta[1:]
}
if (cmd & 0x02) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
offset |= uint(delta[0]) << 8
delta = delta[1:]
}
if (cmd & 0x04) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
offset |= uint(delta[0]) << 16
delta = delta[1:]
}
if (cmd & 0x08) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
offset |= uint(delta[0]) << 24
delta = delta[1:]
}
- return offset, delta
+ return offset, delta, nil
}
-func decodeSize(cmd byte, delta []byte) (uint, []byte) {
+func decodeSize(cmd byte, delta []byte) (uint, []byte, error) {
var sz uint
if (cmd & 0x10) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
sz = uint(delta[0])
delta = delta[1:]
}
if (cmd & 0x20) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
sz |= uint(delta[0]) << 8
delta = delta[1:]
}
if (cmd & 0x40) != 0 {
+ if len(delta) == 0 {
+ return 0, nil, ErrInvalidDelta
+ }
sz |= uint(delta[0]) << 16
delta = delta[1:]
}
@@ -164,7 +215,7 @@ func decodeSize(cmd byte, delta []byte) (uint, []byte) {
sz = 0x10000
}
- return sz, delta
+ return sz, delta, nil
}
func invalidSize(sz, targetSz uint) bool {