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[PPSC-602] CWE-367: TOCTOU race in SafeJoinPath #128

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[PPSC-602] CWE-367: TOCTOU race in SafeJoinPath #128

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13 changes: 11 additions & 2 deletions internal/util/path.go
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Original file line number Diff line number Diff line change
Expand Up @@ -49,14 +49,23 @@ func SanitizePath(p string) (string, error) {
// where a path could be validated before the directory exists and then exploited
// after creation by a malicious symlink or directory structure.
func SafeJoinPath(basePath, relativePath string) (string, error) {
// Verify base path is an existing directory
info, err := os.Stat(basePath)
// Resolve symlinks in basePath to mitigate TOCTOU race conditions (CWE-367).
// By resolving before validation, we ensure the stat check and path join
// operate on the same physical directory.
resolvedBase, err := filepath.EvalSymlinks(basePath)
if err != nil {
return "", fmt.Errorf("cannot resolve base path: %w", err)
}

// Verify resolved base path is an existing directory
info, err := os.Stat(resolvedBase)
if err != nil {
return "", fmt.Errorf("cannot access base path: %w", err)
}
if !info.IsDir() {
return "", errors.New("base path must be a directory")
}
basePath = resolvedBase

if relativePath == "" {
return "", errors.New("empty relative path")
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