util/guest-random: Fix size arg to tail memcpy

We know that in the body of this if statement i is less than len, so
we really should be copying len - i bytes not i - len bytes.

Fix this typo.

Fixes: 8d8404f1564 ("util: Add qemu_guest_getrandom and associated routines")
Signed-off-by: Mark Nelson <mdnelson8@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210709120600.11080-1-mdnelson8@gmail.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

diff --git a/util/guest-random.c b/util/guest-random.c
index 086115bd67026c4ef7b7004d1915ecb2d8cd7fcb..23643f86cc60e940b70a60fa64118ef36342797f 100644 (file)
--- a/util/guest-random.c
+++ b/util/guest-random.c
@@ -38,7 +38,7 @@ static int glib_random_bytes(void *buf, size_t len)
     }
     if (i < len) {
         x = g_rand_int(rand);
-        __builtin_memcpy(buf + i, &x, i - len);
+        __builtin_memcpy(buf + i, &x, len - i);
     }
     return 0;
 }