Memory violation bug in System.Posix.Env.putEnv

putEnv frees the marshaled string after calling c_putenv. This leads to unpredictable behavior, as the string becomes part of the environment and should not be freed.

See SUSv2:

1. .. the string pointed to by string shall become part of the

environment ...

The issue is reproducible with the following QC property:

import           Test.QuickCheck
import           Test.QuickCheck.Property
import           System.Posix.Env
import           Data.IORef
import qualified Data.Map as Map
import           Control.Applicative

isValidKey :: String -> Bool
isValidKey   k = '\NUL' `notElem` k && '=' `notElem` k && (not . null) k

isValidValue :: String -> Bool
isValidValue v = '\NUL' `notElem` v && (not . null) v

main :: IO ()
main = do
  env' <- getEnvironment >>= newIORef . Map.fromList
  quickCheck $ \k v -> isValidKey k ==> isValidValue v ==> morallyDubiousIOProperty $ do
    putEnv (k ++ "=" ++ v)
    modifyIORef env' (Map.insert k v)
    (==) <$> readIORef env' <*> (Map.fromList <$> getEnvironment)

Trac metadata

Trac field	Value
Version	7.4.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/unix
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