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Harden VM against invalid inputs and add security checks #948

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f61c2be
Harden VM against invalid inputs and add security checks
google-labs-jules[bot] Jul 31, 2025
b0cfe69
Update vmhost/contexts/managedType.go
sasurobert Aug 5, 2025
24eb111
Update vmhost/vmhooks/manBufOps.go
sasurobert Aug 5, 2025
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6 changes: 4 additions & 2 deletions test/features/alloc-features/scenarios/managed_buffer_load_slice.scen.json
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,8 @@
]
},
"expect": {
"out": []
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand Down Expand Up @@ -97,7 +98,8 @@
]
},
"expect": {
"out": []
"status": "10",
"message": "str:bad bounds"
}
}
]
Expand Down
4 changes: 2 additions & 2 deletions test/features/basic-features/scenarios/echo_array_u8.scen.json
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Expand Up @@ -54,8 +54,8 @@
},
"expect": {
"out": [],
"status": "4",
"message": "str:argument decode error (s): input too short",
"status": "10",
"message": "str:bad bounds",
"logs": "*",
"gas": "*",
"refund": "*"
Expand Down
6 changes: 4 additions & 2 deletions test/features/basic-features/scenarios/managed_buffer_copy_slice.scen.json
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,8 @@
]
},
"expect": {
"out": []
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand Down Expand Up @@ -97,7 +98,8 @@
]
},
"expect": {
"out": []
"status": "10",
"message": "str:bad bounds"
}
}
]
Expand Down
7 changes: 2 additions & 5 deletions test/features/basic-features/scenarios/storage_mapper_non_fungible_token.scen.json
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Original file line number Diff line number Diff line change
Expand Up @@ -383,11 +383,8 @@
]
},
"expect": {
"out": [
"u8:1|u8:2|u8:3"
],
"status": "",
"logs": "*"
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand Down
42 changes: 6 additions & 36 deletions test/features/composability/scenarios/forwarder_get_esdt_token_data.scen.json
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Original file line number Diff line number Diff line change
Expand Up @@ -179,18 +179,8 @@
]
},
"expect": {
"out": [
"0",
"0",
"false",
"",
"",
"",
"0x0000000000000000000000000000000000000000000000000000000000000000",
"",
""
],
"status": "0"
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand All @@ -206,18 +196,8 @@
]
},
"expect": {
"out": [
"0",
"0",
"false",
"",
"",
"",
"0x0000000000000000000000000000000000000000000000000000000000000000",
"",
""
],
"status": "0"
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand All @@ -233,18 +213,8 @@
]
},
"expect": {
"out": [
"1",
"0",
"false",
"",
"",
"",
"0x0000000000000000000000000000000000000000000000000000000000000000",
"",
""
],
"status": "0"
"status": "10",
"message": "str:bad bounds"
}
},
{
Expand Down
16 changes: 3 additions & 13 deletions test/features/composability/scenarios/forwarder_nft_decode_complex_attributes.scen.json
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Original file line number Diff line number Diff line change
Expand Up @@ -64,8 +64,8 @@
"gasPrice": "0"
},
"expect": {
"out": [],
"status": "0",
"status": "10",
"message": "str:bad bounds",
"gas": "*",
"refund": "*"
}
Expand Down Expand Up @@ -98,19 +98,9 @@
{
"nonce": "1",
"balance": "1"
},
{
"nonce": "2",
"balance": "1",
"creator": "sc:forwarder",
"royalties": "0",
"hash": "str:nft-create-hash-----------------",
"uri": [
"str:nft-create-uri"
]
}
],
"lastNonce": "2",
"lastNonce": "1",
"roles": [
"ESDTRoleNFTCreate"
]
Expand Down
8 changes: 7 additions & 1 deletion vmhost/contexts/managedType.go
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Original file line number Diff line number Diff line change
Expand Up @@ -639,7 +639,13 @@ func (context *managedTypesContext) GetSlice(mBufferHandle int32, startPosition
if !ok {
return nil, vmhost.ErrNoManagedBufferUnderThisHandle
}
if int(lengthOfSlice) > len(mBuffer)-int(startPosition) || lengthOfSlice < 0 || startPosition < 0 {
if startPosition < 0 || lengthOfSlice < 0 {
return nil, vmhost.ErrBadBounds
}
if len(mBuffer) < int(startPosition) {
return nil, vmhost.ErrBadBounds
}
if len(mBuffer)-int(startPosition) < int(lengthOfSlice) {
return nil, vmhost.ErrBadBounds
}
return mBuffer[startPosition:(startPosition + lengthOfSlice)], nil
Expand Down
6 changes: 0 additions & 6 deletions vmhost/hostCore/execution.go
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Original file line number Diff line number Diff line change
Expand Up @@ -690,12 +690,6 @@ func (host *vmHost) CreateNewContract(input *vmcommon.ContractCreateInput, creat
newContractAddress = nil
err = nil

defer func() {
if err != nil {
newContractAddress = nil
}
}()

_, blockchain, metering, output, runtime, _, _ := host.GetContexts()

codeDeployInput := vmhost.CodeDeployInput{
Expand Down
8 changes: 4 additions & 4 deletions vmhost/hosttest/execution_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1081,10 +1081,10 @@ func TestExecution_ManagedBuffers_SetByteSlice(t *testing.T) {
runTestMBufferSetByteSlice(t, true, 0, 26, vmcommon.Ok, []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZ"))

// Bounds exceeded, source remains unchanged lowercase.
runTestMBufferSetByteSlice(t, true, 18, 9, vmcommon.Ok, []byte("abcdefghijklmnopqrstuvwxyz"))
runTestMBufferSetByteSlice(t, true, -1, 2, vmcommon.Ok, []byte("abcdefghijklmnopqrstuvwxyz"))
runTestMBufferSetByteSlice(t, true, 25, 2, vmcommon.Ok, []byte("abcdefghijklmnopqrstuvwxyz"))
runTestMBufferSetByteSlice(t, true, 0, 27, vmcommon.Ok, []byte("abcdefghijklmnopqrstuvwxyz"))
runTestMBufferSetByteSlice(t, true, 18, 9, vmcommon.ExecutionFailed, nil)
runTestMBufferSetByteSlice(t, true, -1, 2, vmcommon.ExecutionFailed, nil)
runTestMBufferSetByteSlice(t, true, 25, 2, vmcommon.ExecutionFailed, nil)
runTestMBufferSetByteSlice(t, true, 0, 27, vmcommon.ExecutionFailed, nil)
}

func runTestMBufferSetByteSliceDeploy(t *testing.T, enabled bool, retCode vmcommon.ReturnCode) {
Expand Down
2 changes: 2 additions & 0 deletions vmhost/vmhooks/bigIntOps.go
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,7 @@ func (context *VMHooksImpl) BigIntGetUnsignedArgument(id int32, destinationHandl

args := runtime.Arguments()
if int32(len(args)) <= id || id < 0 {
context.FailExecution(vmhost.ErrArgIndexOutOfRange)
return
}

Expand All @@ -95,6 +96,7 @@ func (context *VMHooksImpl) BigIntGetSignedArgument(id int32, destinationHandle

args := runtime.Arguments()
if int32(len(args)) <= id || id < 0 {
context.FailExecution(vmhost.ErrArgIndexOutOfRange)
return
}

Expand Down
12 changes: 9 additions & 3 deletions vmhost/vmhooks/manBufOps.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package vmhooks

import (
"bytes"
"fmt"
"math/big"
"strings"

Expand Down Expand Up @@ -164,7 +165,7 @@ func (context *VMHooksImpl) MBufferGetByteSlice(
}

if startingPosition < 0 || sliceLength < 0 || int(startingPosition+sliceLength) > len(sourceBytes) {
// does not fail execution if slice exceeds bounds
context.FailExecution(vmhost.ErrBadBounds)
return 1
}

Expand Down Expand Up @@ -210,7 +211,7 @@ func ManagedBufferCopyByteSliceWithHost(host vmhost.VMHost, sourceHandle int32,
}

if startingPosition < 0 || sliceLength < 0 || int(startingPosition+sliceLength) > len(sourceBytes) {
// does not fail execution if slice exceeds bounds
FailExecution(host, vmhost.ErrBadBounds)
return 1
}

Expand Down Expand Up @@ -359,7 +360,7 @@ func ManagedBufferSetByteSliceWithTypedArgs(host vmhost.VMHost, mBufferHandle in
}

if startingPosition < 0 || dataLength < 0 || int(startingPosition+dataLength) > len(bufferBytes) {
// does not fail execution if slice exceeds bounds
FailExecution(host, vmhost.ErrBadBounds)
return 1
}

Expand Down Expand Up @@ -703,6 +704,11 @@ func (context *VMHooksImpl) MBufferToBigFloat(mBufferHandle, bigFloatHandle int3
}

bigFloat := new(big.Float)
defer func() {
if r := recover(); r != nil {
context.FailExecution(fmt.Errorf("panic in GobDecode: %v", r))
}
}()
err = bigFloat.GobDecode(managedBuffer)
if err != nil {
if !enableEpochsHandler.IsFlagEnabled(vmhost.ValidationOnGobDecodeFlag) &&
Expand Down
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