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Redesign and reimplement the slice out of bounds check using SSA code representation

Browse source 
Signed-off-by: Cosmin Cojocar <gcojocar@adobe.com>
This commit is contained in:
Cosmin Cojocar 2023-09-20 10:04:32 +02:00 committed by Cosmin Cojocar
parent e1278f9572
commit e02e2f6d5b
8 changed files with 461 additions and 510 deletions
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2
README.md
View file

@ -1,7 +1,7 @@
# gosec - Golang Security Checker
Inspects source code for security problems by scanning the Go AST.
Inspects source code for security problems by scanning the Go AST and SSA code representation.
<img src="https://securego.io/img/gosec.png" width="320">

8
analyzer.go
View file

@ -231,12 +231,10 @@ func (gosec *Analyzer) Process(buildTags []string, packagePaths ...string) error
return fmt.Errorf("parsing errors in pkg %q: %w", pkg.Name, err)
}
gosec.CheckRules(pkg)
if on, err := gosec.config.IsGlobalEnabled(SSA); err == nil && on {
gosec.CheckAnalyzers(pkg)
}
}
}
}
sortErrors(gosec.errors)
return nil
}
@ -377,8 +375,10 @@ func (gosec *Analyzer) CheckAnalyzers(pkg *packages.Package) {
continue
}
if result != nil {
if aissue, ok := result.(*issue.Issue); ok {
gosec.updateIssues(aissue, false, []issue.SuppressionInfo{})
if passIssues, ok := result.([]*issue.Issue); ok {
for _, iss := range passIssues {
gosec.updateIssues(iss, false, []issue.SuppressionInfo{})
}
}
}
}

376
analyzers/slice_bounds.go Normal file
View file

@ -0,0 +1,376 @@
// (c) Copyright gosec's authors
//
// 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 analyzers
import (
"errors"
"fmt"
"go/token"
"regexp"
"strconv"
"strings"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/buildssa"
"golang.org/x/tools/go/ssa"
"github.com/securego/gosec/v2/issue"
)
type bound int
const (
lowerUnbounded bound = iota
upperUnbounded
unbounded
upperBounded
)
func newSliceBoundsAnalyzer(id string, description string) *analysis.Analyzer {
return &analysis.Analyzer{
Name: id,
Doc: description,
Run: runSliceBounds,
Requires: []*analysis.Analyzer{buildssa.Analyzer},
}
}
func runSliceBounds(pass *analysis.Pass) (interface{}, error) {
ssaResult, err := getSSAResult(pass)
if err != nil {
return nil, err
}
issues := map[ssa.Instruction]*issue.Issue{}
ifs := map[ssa.If]*ssa.BinOp{}
for _, mcall := range ssaResult.SSA.SrcFuncs {
for _, block := range mcall.DomPreorder() {
for _, instr := range block.Instrs {
switch instr := instr.(type) {
case *ssa.Alloc:
cap, err := extractSliceCapFromAlloc(instr.String())
if err != nil {
break
}
allocRefs := instr.Referrers()
if allocRefs == nil {
break
}
for _, instr := range *allocRefs {
if slice, ok := instr.(*ssa.Slice); ok {
if _, ok := slice.X.(*ssa.Alloc); ok {
if slice.Parent() != nil {
l, h := extractSliceBounds(slice)
newCap := computeSliceNewCap(l, h, cap)
violations := []ssa.Instruction{}
trackSliceBounds(newCap, slice, &violations, ifs)
for _, s := range violations {
switch s := s.(type) {
case *ssa.Slice:
issue := newIssue(
pass.Analyzer.Name,
"slice bounds out of range",
pass.Fset,
s.Pos(),
issue.Low,
issue.High)
issues[s] = issue
case *ssa.IndexAddr:
issue := newIssue(
pass.Analyzer.Name,
"slice index out of range",
pass.Fset,
s.Pos(),
issue.Low,
issue.High)
issues[s] = issue
}
}
}
}
}
}
}
}
}
}
for ifref, binop := range ifs {
bound, value, err := extractBinOpBound(binop)
if err != nil {
continue
}
for i, block := range ifref.Block().Succs {
if i == 1 {
bound = invBound(bound)
}
for _, instr := range block.Instrs {
if _, ok := issues[instr]; ok {
switch bound {
case lowerUnbounded:
break
case upperUnbounded, unbounded:
delete(issues, instr)
case upperBounded:
switch tinstr := instr.(type) {
case *ssa.Slice:
lower, upper := extractSliceBounds(tinstr)
if isSliceInsideBounds(0, value, lower, upper) {
delete(issues, instr)
}
case *ssa.IndexAddr:
indexValue, err := extractIntValue(tinstr.Index.String())
if err != nil {
break
}
if isSliceIndexInsideBounds(0, value, indexValue) {
delete(issues, instr)
}
}
}
}
}
}
}
foundIssues := []*issue.Issue{}
for _, issue := range issues {
foundIssues = append(foundIssues, issue)
}
if len(foundIssues) > 0 {
return foundIssues, nil
}
return nil, nil
}
func trackSliceBounds(cap int, slice ssa.Node, violations *[]ssa.Instruction, ifs map[ssa.If]*ssa.BinOp) {
if violations == nil {
violations = &[]ssa.Instruction{}
}
referrers := slice.Referrers()
if referrers != nil {
for _, refinstr := range *referrers {
switch refinstr := refinstr.(type) {
case *ssa.Slice:
checkAllSlicesBounds(cap, refinstr, violations, ifs)
switch refinstr.X.(type) {
case *ssa.Alloc, *ssa.Parameter:
l, h := extractSliceBounds(refinstr)
newCap := computeSliceNewCap(l, h, cap)
trackSliceBounds(newCap, refinstr, violations, ifs)
}
case *ssa.IndexAddr:
indexValue, err := extractIntValue(refinstr.Index.String())
if err == nil && !isSliceIndexInsideBounds(0, cap, indexValue) {
*violations = append(*violations, refinstr)
}
case *ssa.Call:
if ifref, cond := extractSliceIfLenCondition(refinstr); ifref != nil && cond != nil {
ifs[*ifref] = cond
} else {
parPos := -1
for pos, arg := range refinstr.Call.Args {
if a, ok := arg.(*ssa.Slice); ok && a == slice {
parPos = pos
}
}
if fn, ok := refinstr.Call.Value.(*ssa.Function); ok {
if len(fn.Params) > parPos && parPos > -1 {
param := fn.Params[parPos]
trackSliceBounds(cap, param, violations, ifs)
}
}
}
}
}
}
}
func checkAllSlicesBounds(cap int, slice *ssa.Slice, violations *[]ssa.Instruction, ifs map[ssa.If]*ssa.BinOp) {
if violations == nil {
violations = &[]ssa.Instruction{}
}
sliceLow, sliceHigh := extractSliceBounds(slice)
if !isSliceInsideBounds(0, cap, sliceLow, sliceHigh) {
*violations = append(*violations, slice)
}
switch slice.X.(type) {
case *ssa.Alloc, *ssa.Parameter, *ssa.Slice:
l, h := extractSliceBounds(slice)
newCap := computeSliceNewCap(l, h, cap)
trackSliceBounds(newCap, slice, violations, ifs)
}
references := slice.Referrers()
if references == nil {
return
}
for _, ref := range *references {
switch s := ref.(type) {
case *ssa.Slice:
checkAllSlicesBounds(cap, s, violations, ifs)
switch s.X.(type) {
case *ssa.Alloc, *ssa.Parameter:
l, h := extractSliceBounds(s)
newCap := computeSliceNewCap(l, h, cap)
trackSliceBounds(newCap, s, violations, ifs)
}
}
}
}
func extractSliceIfLenCondition(call *ssa.Call) (*ssa.If, *ssa.BinOp) {
if builtInLen, ok := call.Call.Value.(*ssa.Builtin); ok {
if builtInLen.Name() == "len" {
refs := call.Referrers()
if refs != nil {
for _, ref := range *refs {
if binop, ok := ref.(*ssa.BinOp); ok {
binoprefs := binop.Referrers()
for _, ref := range *binoprefs {
if ifref, ok := ref.(*ssa.If); ok {
return ifref, binop
}
}
}
}
}
}
}
return nil, nil
}
func computeSliceNewCap(l, h, cap int) int {
if l == 0 && h == 0 {
return cap
}
if l > 0 && h == 0 {
return cap - l
}
if l == 0 && h > 0 {
return h
}
return h - l
}
func invBound(bound bound) bound {
switch bound {
case lowerUnbounded:
return upperUnbounded
case upperUnbounded:
return lowerUnbounded
case upperBounded:
return unbounded
case unbounded:
return upperBounded
default:
return unbounded
}
}
func extractBinOpBound(binop *ssa.BinOp) (bound, int, error) {
if binop.X != nil {
if x, ok := binop.X.(*ssa.Const); ok {
value, err := strconv.Atoi(x.Value.String())
if err != nil {
return lowerUnbounded, value, err
}
switch binop.Op {
case token.LSS, token.LEQ:
return upperUnbounded, value, nil
case token.GTR, token.GEQ:
return lowerUnbounded, value, nil
case token.EQL:
return upperBounded, value, nil
case token.NEQ:
return unbounded, value, nil
}
}
}
if binop.Y != nil {
if y, ok := binop.Y.(*ssa.Const); ok {
value, err := strconv.Atoi(y.Value.String())
if err != nil {
return lowerUnbounded, value, err
}
switch binop.Op {
case token.LSS, token.LEQ:
return lowerUnbounded, value, nil
case token.GTR, token.GEQ:
return upperUnbounded, value, nil
case token.EQL:
return upperBounded, value, nil
case token.NEQ:
return unbounded, value, nil
}
}
}
return lowerUnbounded, 0, fmt.Errorf("unable to extract constant from binop")
}
func isSliceIndexInsideBounds(l, h int, index int) bool {
return (l <= index && index < h)
}
func isSliceInsideBounds(l, h int, cl, ch int) bool {
return (l <= cl && h >= ch) && (l <= ch && h >= cl)
}
func extractSliceBounds(slice *ssa.Slice) (int, int) {
var low int
if slice.Low != nil {
l, err := extractIntValue(slice.Low.String())
if err == nil {
low = l
}
}
var high int
if slice.High != nil {
h, err := extractIntValue(slice.High.String())
if err == nil {
high = h
}
}
return low, high
}
func extractIntValue(value string) (int, error) {
parts := strings.Split(value, ":")
if len(parts) != 2 {
return 0, fmt.Errorf("invalid value: %s", value)
}
if parts[1] != "int" {
return 0, fmt.Errorf("invalid value: %s", value)
}
return strconv.Atoi(parts[0])
}
func extractSliceCapFromAlloc(instr string) (int, error) {
re := regexp.MustCompile(`new \[(\d+)\]*`)
var cap int
matches := re.FindAllStringSubmatch(instr, -1)
if matches == nil {
return cap, errors.New("no slice cap found")
}
if len(matches) > 0 {
m := matches[0]
if len(m) > 1 {
return strconv.Atoi(m[1])
}
}
return 0, errors.New("no slice cap found")
}

57
analyzers/ssrf.go
View file

@ -1,57 +0,0 @@
// (c) Copyright gosec's authors
//
// 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 analyzers
import (
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/buildssa"
"golang.org/x/tools/go/ssa"
"github.com/securego/gosec/v2/issue"
)
func newSSRFAnalyzer(id string, description string) *analysis.Analyzer {
return &analysis.Analyzer{
Name: id,
Doc: description,
Run: runSSRF,
Requires: []*analysis.Analyzer{buildssa.Analyzer},
}
}
func runSSRF(pass *analysis.Pass) (interface{}, error) {
ssaResult, err := getSSAResult(pass)
if err != nil {
return nil, err
}
// TODO: implement the analysis
for _, fn := range ssaResult.SSA.SrcFuncs {
for _, block := range fn.DomPreorder() {
for _, instr := range block.Instrs {
switch instr := instr.(type) {
case *ssa.Call:
callee := instr.Call.StaticCallee()
if callee != nil {
ssaResult.Logger.Printf("callee: %s\n", callee)
return newIssue(pass.Analyzer.Name,
"not implemented",
pass.Fset, instr.Call.Pos(), issue.Low, issue.High), nil
}
}
}
}
}
return nil, nil
}

2
analyzers/util.go
View file

@ -38,7 +38,7 @@ type SSAAnalyzerResult struct {
// BuildDefaultAnalyzers returns the default list of analyzers
func BuildDefaultAnalyzers() []*analysis.Analyzer {
return []*analysis.Analyzer{
newSSRFAnalyzer("G107", "URL provided to HTTP request as taint input"),
newSliceBoundsAnalyzer("G602", "Possible slice bounds out of range"),
}
}

1
rules/rulelist.go
View file

@ -107,7 +107,6 @@ func Generate(trackSuppressions bool, filters ...RuleFilter) RuleList {
// memory safety
{"G601", "Implicit memory aliasing in RangeStmt", NewImplicitAliasing},
{"G602", "Slice access out of bounds", NewSliceBoundCheck},
}
ruleMap := make(map[string]RuleDefinition)

410
rules/slice_bounds.go
View file

@ -1,410 +0,0 @@
package rules
import (
"fmt"
"go/ast"
"go/types"
"github.com/securego/gosec/v2"
"github.com/securego/gosec/v2/issue"
)
// sliceOutOfBounds is a rule which checks for slices which are accessed outside their capacity,
// either through indexing it out of bounds or through slice expressions whose low or high index
// are out of bounds.
type sliceOutOfBounds struct {
sliceCaps map[*ast.CallExpr]map[string]*int64 // Capacities of slices. Maps function call -> var name -> value.
currentScope *types.Scope // Current scope. Map is cleared when scope changes.
currentFuncName string // Current function.
funcCallArgs map[string][]*int64 // Caps to load once a func declaration is scanned.
issue.MetaData // Metadata for this rule.
}
// ID returns the rule ID for sliceOutOfBounds: G602.
func (s *sliceOutOfBounds) ID() string {
return s.MetaData.ID
}
func (s *sliceOutOfBounds) Match(node ast.Node, ctx *gosec.Context) (*issue.Issue, error) {
if s.currentScope == nil {
s.currentScope = ctx.Pkg.Scope()
} else if s.currentScope != ctx.Pkg.Scope() {
s.currentScope = ctx.Pkg.Scope()
// Clear slice map, since we are in a new scope
sliceMapNil := make(map[string]*int64)
sliceCaps := make(map[*ast.CallExpr]map[string]*int64)
sliceCaps[nil] = sliceMapNil
s.sliceCaps = sliceCaps
}
switch node := node.(type) {
case *ast.AssignStmt:
return s.matchAssign(node, ctx)
case *ast.SliceExpr:
return s.matchSliceExpr(node, ctx)
case *ast.IndexExpr:
return s.matchIndexExpr(node, ctx)
case *ast.FuncDecl:
s.currentFuncName = node.Name.Name
s.loadArgCaps(node)
case *ast.CallExpr:
if _, ok := node.Fun.(*ast.FuncLit); ok {
// Do nothing with func literals for now.
break
}
sliceMap := make(map[string]*int64)
s.sliceCaps[node] = sliceMap
s.setupCallArgCaps(node, ctx)
}
return nil, nil
}
// updateSliceCaps takes in a variable name and a map of calls we are updating the variables for to the updated values
// and will add it to the sliceCaps map.
func (s *sliceOutOfBounds) updateSliceCaps(varName string, caps map[*ast.CallExpr]*int64) {
for callExpr, cap := range caps {
s.sliceCaps[callExpr][varName] = cap
}
}
// getAllCalls returns all CallExprs that are calls to the given function.
func (s *sliceOutOfBounds) getAllCalls(funcName string, ctx *gosec.Context) []*ast.CallExpr {
calls := []*ast.CallExpr{}
for callExpr := range s.sliceCaps {
if callExpr != nil {
// Compare the names of the function the code is scanning with the current call we are iterating over
_, callFuncName, err := gosec.GetCallInfo(callExpr, ctx)
if err != nil {
continue
}
if callFuncName == funcName {
calls = append(calls, callExpr)
}
}
}
return calls
}
// getSliceCapsForFunc gets all the capacities for slice with given name that are stored for each call to the passed function.
func (s *sliceOutOfBounds) getSliceCapsForFunc(funcName string, varName string, ctx *gosec.Context) map[*ast.CallExpr]*int64 {
caps := make(map[*ast.CallExpr]*int64)
calls := s.getAllCalls(funcName, ctx)
for _, call := range calls {
if callCaps, ok := s.sliceCaps[call]; ok {
caps[call] = callCaps[varName]
}
}
return caps
}
// setupCallArgCaps evaluates and saves the caps for any slices in the args so they can be validated when the function is scanned.
func (s *sliceOutOfBounds) setupCallArgCaps(callExpr *ast.CallExpr, ctx *gosec.Context) {
// Array of caps to be loaded once the function declaration is scanned
funcCallArgs := []*int64{}
// Get function name
_, funcName, err := gosec.GetCallInfo(callExpr, ctx)
if err != nil {
return
}
for _, arg := range callExpr.Args {
switch node := arg.(type) {
case *ast.SliceExpr:
caps := s.evaluateSliceExpr(node, ctx)
// Simplifying assumption: use the lowest capacity. Storing all possible capacities for slices passed
// to a function call would catch the most issues, but would require a data structure like a stack and a
// reworking of the code for scanning itself. Use the lowest capacity, as this would be more likely to
// raise an issue for being out of bounds.
var lowestCap *int64
for _, cap := range caps {
if cap == nil {
continue
}
if lowestCap == nil {
lowestCap = cap
} else if *lowestCap > *cap {
lowestCap = cap
}
}
if lowestCap == nil {
funcCallArgs = append(funcCallArgs, nil)
continue
}
// Now create a map of just this value to add it to the sliceCaps
funcCallArgs = append(funcCallArgs, lowestCap)
case *ast.Ident:
ident := arg.(*ast.Ident)
caps := s.getSliceCapsForFunc(s.currentFuncName, ident.Name, ctx)
var lowestCap *int64
for _, cap := range caps {
if cap == nil {
continue
}
if lowestCap == nil {
lowestCap = cap
} else if *lowestCap > *cap {
lowestCap = cap
}
}
if lowestCap == nil {
funcCallArgs = append(funcCallArgs, nil)
continue
}
// Now create a map of just this value to add it to the sliceCaps
funcCallArgs = append(funcCallArgs, lowestCap)
default:
funcCallArgs = append(funcCallArgs, nil)
}
}
s.funcCallArgs[funcName] = funcCallArgs
}
// loadArgCaps loads caps that were saved for a call to this function.
func (s *sliceOutOfBounds) loadArgCaps(funcDecl *ast.FuncDecl) {
sliceMap := make(map[string]*int64)
funcName := funcDecl.Name.Name
// Create a dummmy call expr for the new function. This is so we can still store args for
// functions which are not explicitly called in the code by other functions (specifically, main).
ident := ast.NewIdent(funcName)
dummyCallExpr := ast.CallExpr{
Fun: ident,
}
argCaps, ok := s.funcCallArgs[funcName]
if !ok || len(argCaps) == 0 {
s.sliceCaps[&dummyCallExpr] = sliceMap
return
}
params := funcDecl.Type.Params.List
if len(params) > len(argCaps) {
return // Length of params and args doesn't match, so don't do anything with this.
}
for it := range params {
capacity := argCaps[it]
if capacity == nil {
continue
}
if len(params[it].Names) == 0 {
continue
}
if paramName := params[it].Names[0]; paramName != nil {
sliceMap[paramName.Name] = capacity
}
}
s.sliceCaps[&dummyCallExpr] = sliceMap
}
// matchSliceMake matches calls to make() and stores the capacity of the new slice in the map to compare against future slice usage.
func (s *sliceOutOfBounds) matchSliceMake(funcCall *ast.CallExpr, sliceName string, ctx *gosec.Context) (*issue.Issue, error) {
_, funcName, err := gosec.GetCallInfo(funcCall, ctx)
if err != nil || funcName != "make" {
return nil, nil
}
var capacityArg int
if len(funcCall.Args) < 2 {
return nil, nil // No size passed
} else if len(funcCall.Args) == 2 {
capacityArg = 1
} else if len(funcCall.Args) == 3 {
capacityArg = 2
} else {
return nil, nil // Unexpected, args should always be 2 or 3
}
// Check if the type of the slice is a map, since they should no be checked.
if _, ok := funcCall.Args[0].(*ast.MapType); ok {
return nil, nil
}
// Check and get the capacity of the slice passed to make. It must be a literal value, since we aren't evaluating the expression.
sliceCapLit, ok := funcCall.Args[capacityArg].(*ast.BasicLit)
if !ok {
return nil, nil
}
capacity, err := gosec.GetInt(sliceCapLit)
if err != nil {
return nil, nil
}
caps := s.getSliceCapsForFunc(s.currentFuncName, sliceName, ctx)
for callExpr := range caps {
caps[callExpr] = &capacity
}
s.updateSliceCaps(sliceName, caps)
return nil, nil
}
// evaluateSliceExpr takes a slice expression and evaluates what the capacity of said slice is for each of the
// calls to the current function. Returns map of the call expressions of each call to the current function to
// the evaluated capacities.
func (s *sliceOutOfBounds) evaluateSliceExpr(node *ast.SliceExpr, ctx *gosec.Context) map[*ast.CallExpr]*int64 {
// Get ident to get name
ident, ok := node.X.(*ast.Ident)
if !ok {
return nil
}
// Get cap of old slice to calculate this new slice's cap
caps := s.getSliceCapsForFunc(s.currentFuncName, ident.Name, ctx)
for callExpr, oldCap := range caps {
if oldCap == nil {
continue
}
// Get and check low value
lowIdent, ok := node.Low.(*ast.BasicLit)
if ok && lowIdent != nil {
low, _ := gosec.GetInt(lowIdent)
newCap := *oldCap - low
caps[callExpr] = &newCap
} else if lowIdent == nil { // If no lower bound, capacity will be same
continue
}
}
return caps
}
// matchSliceAssignment matches slice assignments, calculates capacity of slice if possible to store it in map.
func (s *sliceOutOfBounds) matchSliceAssignment(node *ast.SliceExpr, sliceName string, ctx *gosec.Context) (*issue.Issue, error) {
// First do the normal match that verifies the slice expr is not out of bounds
if i, err := s.matchSliceExpr(node, ctx); err != nil {
return i, fmt.Errorf("There was an error while matching a slice expression to check slice bounds for %s: %w", sliceName, err)
}
// Now that the assignment is (presumably) successfully, we can calculate the capacity and add this new slice to the map
caps := s.evaluateSliceExpr(node, ctx)
s.updateSliceCaps(sliceName, caps)
return nil, nil
}
// matchAssign matches checks if an assignment statement is making a slice, or if it is assigning a slice.
func (s *sliceOutOfBounds) matchAssign(node *ast.AssignStmt, ctx *gosec.Context) (*issue.Issue, error) {
// Check RHS for calls to make() so we can get the actual size of the slice
for it, i := range node.Rhs {
// Get the slice name so we can associate the cap with the slice in the map
sliceIdent, ok := node.Lhs[it].(*ast.Ident)
if !ok {
return nil, nil
}
sliceName := sliceIdent.Name
switch expr := i.(type) {
case *ast.CallExpr: // Check for and handle call to make()
return s.matchSliceMake(expr, sliceName, ctx)
case *ast.SliceExpr: // Handle assignments to a slice
return s.matchSliceAssignment(expr, sliceName, ctx)
}
}
return nil, nil
}
// matchSliceExpr validates that a given slice expression (eg, slice[10:30]) is not out of bounds.
func (s *sliceOutOfBounds) matchSliceExpr(node *ast.SliceExpr, ctx *gosec.Context) (*issue.Issue, error) {
// First get the slice name so we can check the size in our map
ident, ok := node.X.(*ast.Ident)
if !ok {
return nil, nil
}
// Get slice cap from the map to compare it against high and low
caps := s.getSliceCapsForFunc(s.currentFuncName, ident.Name, ctx)
for _, cap := range caps {
if cap == nil {
continue
}
// Get and check high value
highIdent, ok := node.High.(*ast.BasicLit)
if ok && highIdent != nil {
high, _ := gosec.GetInt(highIdent)
if high > *cap {
return ctx.NewIssue(node, s.ID(), s.What, s.Severity, s.Confidence), nil
}
}
// Get and check low value
lowIdent, ok := node.Low.(*ast.BasicLit)
if ok && lowIdent != nil {
low, _ := gosec.GetInt(lowIdent)
if low > *cap {
return ctx.NewIssue(node, s.ID(), s.What, s.Severity, s.Confidence), nil
}
}
}
return nil, nil
}
// matchIndexExpr validates that an index into a slice is not out of bounds.
func (s *sliceOutOfBounds) matchIndexExpr(node *ast.IndexExpr, ctx *gosec.Context) (*issue.Issue, error) {
// First get the slice name so we can check the size in our map
ident, ok := node.X.(*ast.Ident)
if !ok {
return nil, nil
}
// Get slice cap from the map to compare it against high and low
caps := s.getSliceCapsForFunc(s.currentFuncName, ident.Name, ctx)
for _, cap := range caps {
if cap == nil {
continue
}
// Get the index literal
indexIdent, ok := node.Index.(*ast.BasicLit)
if ok && indexIdent != nil {
index, _ := gosec.GetInt(indexIdent)
if index >= *cap {
return ctx.NewIssue(node, s.ID(), s.What, s.Severity, s.Confidence), nil
}
}
}
return nil, nil
}
// NewSliceBoundCheck attempts to find any slices being accessed out of bounds
// by reslicing or by being indexed.
func NewSliceBoundCheck(id string, _ gosec.Config) (gosec.Rule, []ast.Node) {
sliceMap := make(map[*ast.CallExpr]map[string]*int64)
return &sliceOutOfBounds{
sliceCaps: sliceMap,
currentFuncName: "",
funcCallArgs: make(map[string][]*int64),
MetaData: issue.MetaData{
ID: id,
Severity: issue.Medium,
Confidence: issue.Medium,
What: "Potentially accessing slice out of bounds",
},
}, []ast.Node{(*ast.CallExpr)(nil), (*ast.FuncDecl)(nil), (*ast.AssignStmt)(nil), (*ast.SliceExpr)(nil), (*ast.IndexExpr)(nil)}
}

75
testutils/source.go
View file

@ -3861,39 +3861,39 @@ func main() {
}`}, 2, gosec.NewConfig()},
{[]string{`
package main
package main
import "fmt"
import "fmt"
func main() {
func main() {
s := make([]byte, 0, 4)
x := s[:2]
y := x[:10]
fmt.Println(y)
}`}, 1, gosec.NewConfig()},
}`}, 1, gosec.NewConfig()},
{[]string{`
package main
package main
import "fmt"
import "fmt"
func main() {
func main() {
s := make([]int, 0, 4)
doStuff(s)
}
}
func doStuff(x []int) {
func doStuff(x []int) {
newSlice := x[:10]
fmt.Println(newSlice)
}`}, 1, gosec.NewConfig()},
}`}, 1, gosec.NewConfig()},
{[]string{`
package main
package main
import "fmt"
import "fmt"
func main() {
func main() {
s := make([]int, 0, 30)
doStuff(s)
@ -3902,14 +3902,14 @@ func main() {
doStuff(y)
z := y[5:]
doStuff(z)
}
}
func doStuff(x []int) {
func doStuff(x []int) {
newSlice := x[:10]
fmt.Println(newSlice)
newSlice2 := x[:6]
fmt.Println(newSlice2)
}`}, 2, gosec.NewConfig()},
}`}, 2, gosec.NewConfig()},
{[]string{`
package main
@ -3923,6 +3923,49 @@ func main() {
},
}
fmt.Println(testMap)
}`}, 0, gosec.NewConfig()},
{[]string{`
package main
import "fmt"
func main() {
s := make([]byte, 0)
if len(s) > 0 {
fmt.Println(s[0])
}
}`}, 0, gosec.NewConfig()},
{[]string{`
package main
import "fmt"
func main() {
s := make([]byte, 0)
if len(s) > 0 {
fmt.Println("fake test")
}
fmt.Println(s[0])
}`}, 1, gosec.NewConfig()},
{[]string{`
package main
import "fmt"
func main() {
s := make([]int, 16)
for i := 0; i < 17; i++ {
s = append(s, i)
}
if len(s) < 16 {
fmt.Println(s[10:16])
} else {
fmt.Println(s[3:18])
}
fmt.Println(s[0])
for i := range s {
fmt.Println(s[i])
}
}`}, 0, gosec.NewConfig()},
}
)