preserve errno value on success.

If getrandom returns a temporary failure, make sure errno is not polluted when
it succeeds. Thanks to deraadt@ for pointing it out.

2 files changed, 12 insertions, 8 deletions

diff --git a/src/lib/libcrypto/arc4random/getentropy_linux.c b/src/lib/libcrypto/arc4random/getentropy_linux.c
index 76d724af14..4e1a267931 100644
--- a/src/lib/libcrypto/arc4random/getentropy_linux.c
+++ b/src/lib/libcrypto/arc4random/getentropy_linux.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: getentropy_linux.c,v 1.34 2014/08/16 18:42:41 bcook Exp $     */
+/*      $OpenBSD: getentropy_linux.c,v 1.35 2014/08/28 01:00:57 bcook Exp $     */
 
 /*
  * Copyright (c) 2014 Theo de Raadt <deraadt@openbsd.org>
@@ -194,6 +194,7 @@ gotdata(char *buf, size_t len)
 static int
 getentropy_getrandom(void *buf, size_t len)
 {
+        int pre_errno = errno;
         int ret;
         if (len > 256)
                 return (-1);
@@ -201,9 +202,10 @@ getentropy_getrandom(void *buf, size_t len)
                 ret = syscall(SYS_getrandom, buf, len, 0);
         } while (ret == -1 && errno == EINTR);
 
-        if (ret == len)
-                return (0);
-        return (-1);
+        if (ret != len)
+                return (-1);
+        errno = pre_errno;
+        return (0);
 }
 #endif
 
diff --git a/src/lib/libcrypto/crypto/getentropy_linux.c b/src/lib/libcrypto/crypto/getentropy_linux.c
index 76d724af14..4e1a267931 100644
--- a/src/lib/libcrypto/crypto/getentropy_linux.c
+++ b/src/lib/libcrypto/crypto/getentropy_linux.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: getentropy_linux.c,v 1.34 2014/08/16 18:42:41 bcook Exp $     */
+/*      $OpenBSD: getentropy_linux.c,v 1.35 2014/08/28 01:00:57 bcook Exp $     */
 
 /*
  * Copyright (c) 2014 Theo de Raadt <deraadt@openbsd.org>
@@ -194,6 +194,7 @@ gotdata(char *buf, size_t len)
 static int
 getentropy_getrandom(void *buf, size_t len)
 {
+        int pre_errno = errno;
         int ret;
         if (len > 256)
                 return (-1);
@@ -201,9 +202,10 @@ getentropy_getrandom(void *buf, size_t len)
                 ret = syscall(SYS_getrandom, buf, len, 0);
         } while (ret == -1 && errno == EINTR);
 
-        if (ret == len)
-                return (0);
-        return (-1);
+        if (ret != len)
+                return (-1);
+        errno = pre_errno;
+        return (0);
 }
 #endif