scryptenc: free the expanded AES key when a write fails

Makefile.am

@@ -309,6 +309,7 @@ EXTRA_DIST=								\
 	tests/08-passphrase-file.sh					\
 	tests/09-explicit-params.sh					\
 	tests/10-check-params.sh					\
+	tests/13-write-error.sh						\
 	tests/shared_test_functions.sh					\
 	tests/shared_valgrind_functions.sh				\
 	tests/test_scrypt.sh						\

lib/scryptenc/scryptenc.c

@@ -651,6 +651,7 @@ scryptenc_file(FILE * infile, FILE * outfile,
 		HMAC_SHA256_Update(&hctx, buf, readlen);
 		if (fwrite(buf, 1, readlen, outfile) < readlen) {
 			crypto_aesctr_free(AES);
+			crypto_aes_key_free(key_enc_exp);
 			rc = SCRYPT_EWRFILE;
 			goto err1;
 		}
@@ -869,6 +870,7 @@ scryptdec_file_copy(struct scryptdec_file_cookie * C, FILE * outfile)
 		crypto_aesctr_stream(AES, buf, buf, buflen - 32);
 		if (fwrite(buf, 1, buflen - 32, outfile) < buflen - 32) {
 			crypto_aesctr_free(AES);
+			crypto_aes_key_free(key_enc_exp);
 			rc = SCRYPT_EWRFILE;
 			goto err0;
 		}

tests/13-write-error.sh

@@ -0,0 +1,64 @@
+#!/bin/sh
+
+### Constants
+c_valgrind_min=1
+reference_file="${scriptdir}/verify-strings/test_scrypt.good"
+large_file="${s_basename}-large.txt"
+large_enc="${s_basename}-large.enc"
+stderr_enc="${s_basename}-enc.stderr"
+stderr_dec="${s_basename}-dec.stderr"
+
+# Explicit parameters keep the key derivation cheap, and -f skips the
+# resource checks, which would otherwise measure the CPU speed every time.
+fast_params="-f --logN 10 -r 1 -p 1"
+
+scenario_cmd() {
+	# Build an input which is larger than stdio's buffer, so that a write
+	# failure happens inside the encrypt and decrypt loops rather than
+	# when the output is flushed at the end.
+	i=0
+	while [ "${i}" -lt 128 ]; do
+		cat "${reference_file}"
+		i=$((i + 1))
+	done > "${large_file}"
+
+	# Encrypting it to a writable file must work.  This also gives us a
+	# ciphertext which is larger than stdio's buffer.
+	setup_check "scrypt enc large file"
+	echo "${password}" | ${c_valgrind_cmd} "${bindir}/scrypt"	\
+	    enc ${fast_params} --passphrase dev:stdin-once		\
+	    "${large_file}" "${large_enc}"
+	echo $? > "${c_exitfile}"
+
+	# The write-error paths need an output file which never accepts data.
+	# /dev/full is not portable, so stop here if we don't have it.
+	if ! [ -c /dev/full ] || ! [ -w /dev/full ]; then
+		return
+	fi
+
+	setup_check "scrypt enc write error"
+	(
+		echo "${password}" | ${c_valgrind_cmd} "${bindir}/scrypt" \
+		    enc ${fast_params} --passphrase dev:stdin-once	\
+		    "${large_file}" /dev/full				\
+		    2> "${stderr_enc}"
+		expected_exitcode 1 $? > "${c_exitfile}"
+	)
+
+	setup_check "scrypt enc write error message"
+	grep -q "scrypt: Error writing file: /dev/full" "${stderr_enc}"
+	echo $? > "${c_exitfile}"
+
+	setup_check "scrypt dec write error"
+	(
+		echo "${password}" | ${c_valgrind_cmd} "${bindir}/scrypt" \
+		    dec -f --passphrase dev:stdin-once			\
+		    "${large_enc}" /dev/full				\
+		    2> "${stderr_dec}"
+		expected_exitcode 1 $? > "${c_exitfile}"
+	)
+
+	setup_check "scrypt dec write error message"
+	grep -q "scrypt: Error writing file: /dev/full" "${stderr_dec}"
+	echo $? > "${c_exitfile}"
+}