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random-util: always cast from smaller to bigger type when comparing

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When we compare two size values, let's make sure we cast from the
smaller to the bigger type first, if both types differ, rather than the
reverse in order to not run into overflows.
This commit is contained in:
Lennart Poettering
2017-07-11 10:37:40 +02:00
parent f3b57eaf45
commit 7b54715d19
1 changed files with 4 additions and 4 deletions
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src/basic/random-util.c
+4 -4
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@@ -46,8 +46,8 @@ int acquire_random_bytes(void *p, size_t n, bool high_quality_required) {
static int have_syscall = -1;
_cleanup_close_ int fd = -1;
int r;
unsigned already_done = 0;
int r;
/* Gathers some randomness from the kernel. This call will never block. If
* high_quality_required, it will always return some data from the kernel,
@@ -61,7 +61,7 @@ int acquire_random_bytes(void *p, size_t n, bool high_quality_required) {
r = getrandom(p, n, GRND_NONBLOCK);
if (r > 0) {
have_syscall = true;
if (r == (int) n)
if ((size_t) r == n)
return 0;
if (!high_quality_required) {
/* Fill in the remaing bytes using pseudorandom values */
@@ -147,11 +147,11 @@ void pseudorandom_bytes(void *p, size_t n) {
rr = (unsigned) rand();
#if RAND_STEP >= 3
if (q - (uint8_t*) p + 2 < (ptrdiff_t) n)
if ((size_t) (q - (uint8_t*) p + 2) < n)
q[2] = rr >> 16;
#endif
#if RAND_STEP >= 2
if (q - (uint8_t*) p + 1 < (ptrdiff_t) n)
if ((size_t) (q - (uint8_t*) p + 1) < n)
q[1] = rr >> 8;
#endif
q[0] = rr;