get_random_data() can return NULL (for instance, if we can't open /dev/random

[u/mdw/putty] / cmdgen.c

diff --git a/cmdgen.c b/cmdgen.c
index d8d5a94..9aa585f 100644 (file)
--- a/cmdgen.c
+++ b/cmdgen.c
@@ -640,6 +640,11 @@ int main(int argc, char **argv)
 
        random_ref();
        entropy = get_random_data(bits / 8);
+       if (!entropy) {
+           fprintf(stderr, "puttygen: failed to collect entropy, "
+                   "could not generate key\n");
+           return 1;
+       }
        random_add_heavynoise(entropy, bits / 8);
        memset(entropy, 0, bits/8);
        sfree(entropy);