[Qemu-devel] [PATCH 2/6] crypto: clear out buffer after timing pbkdf algorithm

[Daniel P. Berrange]

The 'out' buffer will hold a key derived from master
password, so it is best practice to clear this buffer
when no longer required.

Signed-off-by: Daniel P. Berrange <address@hidden>
---
 crypto/pbkdf.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/crypto/pbkdf.c b/crypto/pbkdf.c
index 695cc35..35dccc2 100644
--- a/crypto/pbkdf.c
+++ b/crypto/pbkdf.c
@@ -67,13 +67,14 @@ int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
                                const uint8_t *salt, size_t nsalt,
                                Error **errp)
 {
+    int ret = -1;
     uint8_t out[32];
     long long int iterations = (1 << 15);
     unsigned long long delta_ms, start_ms, end_ms;
 
     while (1) {
         if (qcrypto_pbkdf2_get_thread_cpu(&start_ms, errp) < 0) {
-            return -1;
+            goto cleanup;
         }
         if (qcrypto_pbkdf2(hash,
                            key, nkey,
@@ -81,10 +82,10 @@ int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
                            iterations,
                            out, sizeof(out),
                            errp) < 0) {
-            return -1;
+            goto cleanup;
         }
         if (qcrypto_pbkdf2_get_thread_cpu(&end_ms, errp) < 0) {
-            return -1;
+            goto cleanup;
         }
 
         delta_ms = end_ms - start_ms;
@@ -103,8 +104,12 @@ int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
     if (iterations > INT32_MAX) {
         error_setg(errp, "Iterations %lld too large for a 32-bit int",
                    iterations);
-        return -1;
+        goto cleanup;
     }
 
-    return iterations;
+    ret = iterations;
+
+ cleanup:
+    memset(out, 0, sizeof(out));
+    return ret;
 }
-- 
2.7.4