82 lines
2.8 KiB
Go
82 lines
2.8 KiB
Go
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package sa1031
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import (
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"go/constant"
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"go/token"
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"honnef.co/go/tools/analysis/callcheck"
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"honnef.co/go/tools/analysis/lint"
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"honnef.co/go/tools/go/ir"
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"honnef.co/go/tools/go/ir/irutil"
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"honnef.co/go/tools/internal/passes/buildir"
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"honnef.co/go/tools/knowledge"
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"golang.org/x/tools/go/analysis"
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)
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var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
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Analyzer: &analysis.Analyzer{
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Name: "SA1031",
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Requires: []*analysis.Analyzer{buildir.Analyzer},
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Run: callcheck.Analyzer(checkEncodeRules),
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},
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Doc: &lint.RawDocumentation{
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Title: `Overlapping byte slices passed to an encoder`,
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Text: `In an encoding function of the form \'Encode(dst, src)\', \'dst\' and
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\'src\' were found to reference the same memory. This can result in
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\'src\' bytes being overwritten before they are read, when the encoder
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writes more than one byte per \'src\' byte.`,
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Since: "2024.1",
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Severity: lint.SeverityWarning,
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MergeIf: lint.MergeIfAny,
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},
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})
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var Analyzer = SCAnalyzer.Analyzer
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var checkEncodeRules = map[string]callcheck.Check{
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"encoding/ascii85.Encode": checkNonOverlappingDstSrc(knowledge.Arg("encoding/ascii85.Encode.dst"), knowledge.Arg("encoding/ascii85.Encode.src")),
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"(*encoding/base32.Encoding).Encode": checkNonOverlappingDstSrc(knowledge.Arg("(*encoding/base32.Encoding).Encode.dst"), knowledge.Arg("(*encoding/base32.Encoding).Encode.src")),
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"(*encoding/base64.Encoding).Encode": checkNonOverlappingDstSrc(knowledge.Arg("(*encoding/base64.Encoding).Encode.dst"), knowledge.Arg("(*encoding/base64.Encoding).Encode.src")),
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"encoding/hex.Encode": checkNonOverlappingDstSrc(knowledge.Arg("encoding/hex.Encode.dst"), knowledge.Arg("encoding/hex.Encode.src")),
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}
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func checkNonOverlappingDstSrc(dstArg, srcArg int) callcheck.Check {
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return func(call *callcheck.Call) {
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dst := call.Args[dstArg]
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src := call.Args[srcArg]
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_, dstConst := irutil.Flatten(dst.Value.Value).(*ir.Const)
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_, srcConst := irutil.Flatten(src.Value.Value).(*ir.Const)
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if dstConst || srcConst {
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// one of the arguments is nil, therefore overlap is not possible
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return
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}
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if dst.Value == src.Value {
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// simple case of f(b, b)
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dst.Invalid("overlapping dst and src")
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return
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}
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dstSlice, ok := irutil.Flatten(dst.Value.Value).(*ir.Slice)
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if !ok {
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return
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}
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srcSlice, ok := irutil.Flatten(src.Value.Value).(*ir.Slice)
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if !ok {
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return
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}
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if irutil.Flatten(dstSlice.X) != irutil.Flatten(srcSlice.X) {
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// differing underlying arrays, all is well
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return
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}
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l1 := irutil.Flatten(dstSlice.Low)
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l2 := irutil.Flatten(srcSlice.Low)
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c1, ok1 := l1.(*ir.Const)
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c2, ok2 := l2.(*ir.Const)
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if l1 == l2 || (ok1 && ok2 && constant.Compare(c1.Value, token.EQL, c2.Value)) {
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// dst and src are the same slice, and have the same lower bound
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dst.Invalid("overlapping dst and src")
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return
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}
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}
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}
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