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Limit recursion depth and bump dependencies #2405

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161d186
Implement recursion limit in reader
hdm May 31, 2026
c18e9e1
Bump dependencies for security alerts
hdm May 31, 2026
b01ba42
Reverse unintended go version bump
hdm May 31, 2026
6031b80
Address PR feedback
hdm May 31, 2026
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29 changes: 29 additions & 0 deletions bson/unmarshal_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ package bson

import (
"bytes"
"errors"
"math/rand"
"reflect"
"sync"
Expand Down Expand Up @@ -39,6 +40,34 @@ func TestUnmarshal(t *testing.T) {
}
}

func TestUnmarshalRejectsTooDeepDocumentNesting(t *testing.T) {
inner := bsoncore.BuildDocument(nil, bsoncore.AppendInt32Element(nil, "a", 1))
for depth := 1; depth < maxDocumentNestingDepth+1; depth++ {
inner = bsoncore.BuildDocument(nil, bsoncore.AppendDocumentElement(nil, "a", inner))
}

var got M
err := Unmarshal(inner, &got)
if !errors.Is(err, errMaxDocumentNestingDepth) {
t.Fatalf("expected errMaxDocumentNestingDepth, got %v", err)
}
}

func TestUnmarshalRejectsTooDeepArrayNesting(t *testing.T) {
inner := bsoncore.BuildArray(nil, bsoncore.Value{Type: bsoncore.TypeInt32, Data: bsoncore.AppendInt32(nil, 1)})
for depth := 1; depth < maxDocumentNestingDepth+1; depth++ {
inner = bsoncore.BuildArray(nil, bsoncore.Value{Type: bsoncore.TypeArray, Data: inner})
}

data := bsoncore.BuildDocument(nil, bsoncore.AppendArrayElement(nil, "a", inner))

var got M
err := Unmarshal(data, &got)
if !errors.Is(err, errMaxDocumentNestingDepth) {
t.Fatalf("expected errMaxDocumentNestingDepth, got %v", err)
}
}

func TestUnmarshalWithRegistry(t *testing.T) {
t.Parallel()

Expand Down
48 changes: 44 additions & 4 deletions bson/value_reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -60,12 +60,23 @@ type vrState struct {
mode mode
vType Type
end int64
depth int
}

const maxDocumentNestingDepth = 100

var errMaxDocumentNestingDepth = errors.New("maximum BSON nesting depth exceeded")

var vrPool = sync.Pool{
New: func() any {
stack := make([]vrState, 1, 5)
stack[0] = vrState{
mode: mTopLevel,
depth: 1,
}

return &valueReader{
stack: make([]vrState, 1, 5),
stack: stack,
}
},
}
Expand Down Expand Up @@ -103,7 +114,8 @@ func putBufferedDocumentReader(vr *valueReader) {
func NewDocumentReader(r io.Reader) ValueReader {
stack := make([]vrState, 1, 5)
stack[0] = vrState{
mode: mTopLevel,
mode: mTopLevel,
depth: 1,
}

return &valueReader{
Expand Down Expand Up @@ -141,13 +153,22 @@ func newBufferedDocumentReader(b []byte) *valueReader {
}

vr.stack[0] = vrState{
mode: mTopLevel,
end: int64(len(b)),
mode: mTopLevel,
end: int64(len(b)),
depth: 1,
}
Comment thread
hdm marked this conversation as resolved.

return vr
}

func (vr *valueReader) nextContainerDepth() (int, error) {
depth := vr.stack[vr.frame].depth + 1
if depth > maxDocumentNestingDepth {
return 0, errMaxDocumentNestingDepth
}
return depth, nil
}

func (vr *valueReader) advanceFrame() {
if vr.frame+1 >= int64(len(vr.stack)) { // We need to grow the stack
length := len(vr.stack)
Expand Down Expand Up @@ -366,6 +387,11 @@ func (vr *valueReader) ReadArray() (ArrayReader, error) {
return nil, err
}

depth, err := vr.nextContainerDepth()
if err != nil {
return nil, err
}

// Push a new frame for the array.
vr.advanceFrame()

Expand All @@ -378,6 +404,7 @@ func (vr *valueReader) ReadArray() (ArrayReader, error) {
// Compute the end position: current position + total size - length.
vr.stack[vr.frame].mode = mArray
vr.stack[vr.frame].end = vr.src.pos() + int64(size) - 4
vr.stack[vr.frame].depth = depth

return vr, nil
}
Expand Down Expand Up @@ -469,6 +496,11 @@ func (vr *valueReader) ReadDocument() (DocumentReader, error) {
return nil, vr.invalidTransitionErr(mDocument, "ReadDocument", []mode{mTopLevel, mElement, mValue})
}

depth, err := vr.nextContainerDepth()
if err != nil {
return nil, err
}

vr.advanceFrame()

size, err := vr.readLength()
Expand All @@ -478,6 +510,7 @@ func (vr *valueReader) ReadDocument() (DocumentReader, error) {

vr.stack[vr.frame].mode = mDocument
vr.stack[vr.frame].end = int64(size) + vr.src.pos() - 4
vr.stack[vr.frame].depth = depth

return vr, nil
}
Expand Down Expand Up @@ -506,6 +539,10 @@ func (vr *valueReader) ReadCodeWithScope() (string, DocumentReader, error) {
}

code := string(buf[:len(buf)-1])
depth, err := vr.nextContainerDepth()
if err != nil {
return "", nil, err
}
vr.advanceFrame()

// Use readLength to ensure that we are not out of bounds.
Expand All @@ -516,6 +553,7 @@ func (vr *valueReader) ReadCodeWithScope() (string, DocumentReader, error) {

vr.stack[vr.frame].mode = mCodeWithScope
vr.stack[vr.frame].end = vr.src.pos() + int64(size) - 4
vr.stack[vr.frame].depth = depth

// The total length should equal:
// 4 (total length) + strLength + 4 (the length of str itself) + (document length)
Expand Down Expand Up @@ -833,6 +871,7 @@ func (vr *valueReader) ReadElement() (string, ValueReader, error) {

vr.stack[vr.frame].mode = mElement
vr.stack[vr.frame].vType = Type(t)
vr.stack[vr.frame].depth = vr.stack[vr.frame-1].depth
return name, vr, nil
}

Expand Down Expand Up @@ -868,6 +907,7 @@ func (vr *valueReader) ReadValue() (ValueReader, error) {

vr.stack[vr.frame].mode = mValue
vr.stack[vr.frame].vType = Type(t)
vr.stack[vr.frame].depth = vr.stack[vr.frame-1].depth
return vr, nil
}

Expand Down
10 changes: 5 additions & 5 deletions go.mod
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Original file line number Diff line number Diff line change
@@ -1,21 +1,21 @@
module go.mongodb.org/mongo-driver/v2

go 1.19
go 1.21

require (
github.com/davecgh/go-spew v1.1.1
github.com/google/go-cmp v0.6.0
github.com/klauspost/compress v1.17.6
github.com/klauspost/compress v1.18.6
github.com/xdg-go/scram v1.2.0
github.com/xdg-go/stringprep v1.0.4
github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78
golang.org/x/crypto v0.33.0
golang.org/x/sync v0.11.0
golang.org/x/crypto v0.52.0
golang.org/x/sync v0.20.0
)

require (
github.com/xdg-go/pbkdf2 v1.0.0 // indirect
golang.org/x/text v0.22.0 // indirect
golang.org/x/text v0.37.0 // indirect
)

replace golang.org/x/net/http2 => golang.org/x/net/http2 v0.23.0 // GODRIVER-3225
8 changes: 8 additions & 0 deletions go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/klauspost/compress v1.17.6 h1:60eq2E/jlfwQXtvZEeBUYADs+BwKBWURIY+Gj2eRGjI=
github.com/klauspost/compress v1.17.6/go.mod h1:/dCuZOvVtNoHsyb+cuJD3itjs3NbnF6KH9zAO4BDxPM=
github.com/klauspost/compress v1.18.6 h1:2jupLlAwFm95+YDR+NwD2MEfFO9d4z4Prjl1XXDjuao=
github.com/klauspost/compress v1.18.6/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
github.com/xdg-go/pbkdf2 v1.0.0 h1:Su7DPu48wXMwC3bs7MCNG+z4FhcyEuz5dlvchbq0B0c=
github.com/xdg-go/pbkdf2 v1.0.0/go.mod h1:jrpuAogTd400dnrH08LKmI/xc1MbPOebTwRqcT5RDeI=
github.com/xdg-go/scram v1.2.0 h1:bYKF2AEwG5rqd1BumT4gAnvwU/M9nBp2pTSxeZw7Wvs=
Expand All @@ -17,6 +19,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
golang.org/x/crypto v0.33.0 h1:IOBPskki6Lysi0lo9qQvbxiQ+FvsCC/YWOecCHAixus=
golang.org/x/crypto v0.33.0/go.mod h1:bVdXmD7IV/4GdElGPozy6U7lWdRXA4qyRVGJV57uQ5M=
golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
Expand All @@ -25,6 +29,8 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.11.0 h1:GGz8+XQP4FvTTrjZPzNKTMFtSXH80RAzG+5ghFPgK9w=
golang.org/x/sync v0.11.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
Expand All @@ -38,6 +44,8 @@ golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
golang.org/x/text v0.37.0 h1:Cqjiwd9eSg8e0QAkyCaQTNHFIIzWtidPahFWR83rTrc=
golang.org/x/text v0.37.0/go.mod h1:a5sjxXGs9hsn/AJVwuElvCAo9v8QYLzvavO5z2PiM38=
golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
Expand Down