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[release-branch.go1.23] encoding/gob: cover missed cases when checking ignore depth

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This change makes sure that we are properly checking the ignored field
recursion depth in decIgnoreOpFor consistently. This prevents stack
exhaustion when attempting to decode a message that contains an
extremely deeply nested struct which is ignored.

Thanks to Md Sakib Anwar of The Ohio State University (anwar.40@osu.edu)
for reporting this issue.

Updates #69139
Fixes #69145
Fixes CVE-2024-34156

Change-Id: Iacce06be95a5892b3064f1c40fcba2e2567862d6
Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/1440
Reviewed-by: Russ Cox <rsc@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
(cherry picked from commit 9f2ea73c5f2a7056b7da5d579a485a7216f4b20a)
Reviewed-on: https://go-internal-review.googlesource.com/c/go/+/1581
Commit-Queue: Roland Shoemaker <bracewell@google.com>
Reviewed-by: Tatiana Bradley <tatianabradley@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/611176
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@google.com>
This commit is contained in:
Roland Shoemaker 2024-05-03 09:21:39 -04:00 committed by Gopher Robot
parent 53487e5477
commit fa8ff1a46d
3 changed files with 27 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/encoding/gob/decode.go
View File

@ -911,8 +911,11 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string, inProg
var maxIgnoreNestingDepth = 10000
// decIgnoreOpFor returns the decoding op for a field that has no destination.
func (dec *Decoder) decIgnoreOpFor(wireId typeId, inProgress map[typeId]*decOp, depth int) *decOp {
if depth > maxIgnoreNestingDepth {
func (dec *Decoder) decIgnoreOpFor(wireId typeId, inProgress map[typeId]*decOp) *decOp {
// Track how deep we've recursed trying to skip nested ignored fields.
dec.ignoreDepth++
defer func() { dec.ignoreDepth-- }()
if dec.ignoreDepth > maxIgnoreNestingDepth {
error_(errors.New("invalid nesting depth"))
}
// If this type is already in progress, it's a recursive type (e.g. map[string]*T).
@ -938,7 +941,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId, inProgress map[typeId]*decOp,
errorf("bad data: undefined type %s", wireId.string())
case wire.ArrayT != nil:
elemId := wire.ArrayT.Elem
elemOp := dec.decIgnoreOpFor(elemId, inProgress, depth+1)
elemOp := dec.decIgnoreOpFor(elemId, inProgress)
op = func(i *decInstr, state *decoderState, value reflect.Value) {
state.dec.ignoreArray(state, *elemOp, wire.ArrayT.Len)
}
@ -946,15 +949,15 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId, inProgress map[typeId]*decOp,
case wire.MapT != nil:
keyId := dec.wireType[wireId].MapT.Key
elemId := dec.wireType[wireId].MapT.Elem
keyOp := dec.decIgnoreOpFor(keyId, inProgress, depth+1)
elemOp := dec.decIgnoreOpFor(elemId, inProgress, depth+1)
keyOp := dec.decIgnoreOpFor(keyId, inProgress)
elemOp := dec.decIgnoreOpFor(elemId, inProgress)
op = func(i *decInstr, state *decoderState, value reflect.Value) {
state.dec.ignoreMap(state, *keyOp, *elemOp)
}
case wire.SliceT != nil:
elemId := wire.SliceT.Elem
elemOp := dec.decIgnoreOpFor(elemId, inProgress, depth+1)
elemOp := dec.decIgnoreOpFor(elemId, inProgress)
op = func(i *decInstr, state *decoderState, value reflect.Value) {
state.dec.ignoreSlice(state, *elemOp)
}
@ -1115,7 +1118,7 @@ func (dec *Decoder) compileSingle(remoteId typeId, ut *userTypeInfo) (engine *de
func (dec *Decoder) compileIgnoreSingle(remoteId typeId) *decEngine {
engine := new(decEngine)
engine.instr = make([]decInstr, 1) // one item
op := dec.decIgnoreOpFor(remoteId, make(map[typeId]*decOp), 0)
op := dec.decIgnoreOpFor(remoteId, make(map[typeId]*decOp))
ovfl := overflow(dec.typeString(remoteId))
engine.instr[0] = decInstr{*op, 0, nil, ovfl}
engine.numInstr = 1
@ -1160,7 +1163,7 @@ func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEn
localField, present := srt.FieldByName(wireField.Name)
// TODO(r): anonymous names
if !present || !isExported(wireField.Name) {
op := dec.decIgnoreOpFor(wireField.Id, make(map[typeId]*decOp), 0)
op := dec.decIgnoreOpFor(wireField.Id, make(map[typeId]*decOp))
engine.instr[fieldnum] = decInstr{*op, fieldnum, nil, ovfl}
continue
}

2
src/encoding/gob/decoder.go
View File

@ -35,6 +35,8 @@ type Decoder struct {
freeList *decoderState // list of free decoderStates; avoids reallocation
countBuf []byte // used for decoding integers while parsing messages
err error
// ignoreDepth tracks the depth of recursively parsed ignored fields
ignoreDepth int
}
// NewDecoder returns a new decoder that reads from the [io.Reader].

14
src/encoding/gob/gobencdec_test.go
View File

@ -806,6 +806,8 @@ func TestIgnoreDepthLimit(t *testing.T) {
defer func() { maxIgnoreNestingDepth = oldNestingDepth }()
b := new(bytes.Buffer)
enc := NewEncoder(b)
// Nested slice
typ := reflect.TypeFor[int]()
nested := reflect.ArrayOf(1, typ)
for i := 0; i < 100; i++ {
@ -819,4 +821,16 @@ func TestIgnoreDepthLimit(t *testing.T) {
if err := dec.Decode(&output); err == nil || err.Error() != expectedErr {
t.Errorf("Decode didn't fail with depth limit of 100: want %q, got %q", expectedErr, err)
}
// Nested struct
nested = reflect.StructOf([]reflect.StructField{{Name: "F", Type: typ}})
for i := 0; i < 100; i++ {
nested = reflect.StructOf([]reflect.StructField{{Name: "F", Type: nested}})
}
badStruct = reflect.New(reflect.StructOf([]reflect.StructField{{Name: "F", Type: nested}}))
enc.Encode(badStruct.Interface())
dec = NewDecoder(b)
if err := dec.Decode(&output); err == nil || err.Error() != expectedErr {
t.Errorf("Decode didn't fail with depth limit of 100: want %q, got %q", expectedErr, err)
}
}