gosec/rules/integer_overflow.go
2023-03-20 10:25:45 +01:00

90 lines
2.8 KiB
Go

// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rules
import (
"fmt"
"go/ast"
"github.com/securego/gosec/v2"
"github.com/securego/gosec/v2/issue"
)
type integerOverflowCheck struct {
issue.MetaData
calls gosec.CallList
}
func (i *integerOverflowCheck) ID() string {
return i.MetaData.ID
}
func (i *integerOverflowCheck) Match(node ast.Node, ctx *gosec.Context) (*issue.Issue, error) {
var atoiVarObj map[*ast.Object]ast.Node
// To check multiple lines, ctx.PassedValues is used to store temporary data.
if _, ok := ctx.PassedValues[i.ID()]; !ok {
atoiVarObj = make(map[*ast.Object]ast.Node)
ctx.PassedValues[i.ID()] = atoiVarObj
} else if pv, ok := ctx.PassedValues[i.ID()].(map[*ast.Object]ast.Node); ok {
atoiVarObj = pv
} else {
return nil, fmt.Errorf("PassedValues[%s] of Context is not map[*ast.Object]ast.Node, but %T", i.ID(), ctx.PassedValues[i.ID()])
}
// strconv.Atoi is a common function.
// To reduce false positives, This rule detects code which is converted to int32/int16 only.
switch n := node.(type) {
case *ast.AssignStmt:
for _, expr := range n.Rhs {
if callExpr, ok := expr.(*ast.CallExpr); ok && i.calls.ContainsPkgCallExpr(callExpr, ctx, false) != nil {
if idt, ok := n.Lhs[0].(*ast.Ident); ok && idt.Name != "_" {
// Example:
// v, _ := strconv.Atoi("1111")
// Add v's Obj to atoiVarObj map
atoiVarObj[idt.Obj] = n
}
}
}
case *ast.CallExpr:
if fun, ok := n.Fun.(*ast.Ident); ok {
if fun.Name == "int32" || fun.Name == "int16" {
if idt, ok := n.Args[0].(*ast.Ident); ok {
if _, ok := atoiVarObj[idt.Obj]; ok {
// Detect int32(v) and int16(v)
return ctx.NewIssue(n, i.ID(), i.What, i.Severity, i.Confidence), nil
}
}
}
}
}
return nil, nil
}
// NewIntegerOverflowCheck detects if there is potential Integer OverFlow
func NewIntegerOverflowCheck(id string, _ gosec.Config) (gosec.Rule, []ast.Node) {
calls := gosec.NewCallList()
calls.Add("strconv", "Atoi")
return &integerOverflowCheck{
MetaData: issue.MetaData{
ID: id,
Severity: issue.High,
Confidence: issue.Medium,
What: "Potential Integer overflow made by strconv.Atoi result conversion to int16/32",
},
calls: calls,
}, []ast.Node{(*ast.FuncDecl)(nil), (*ast.AssignStmt)(nil), (*ast.CallExpr)(nil)}
}