From 7b54715d19daeb2768362f4fc0d5192ed8af3ced Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Tue, 11 Jul 2017 10:35:47 +0200 Subject: [PATCH] random-util: always cast from smaller to bigger type when comparing 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. --- src/basic/random-util.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/basic/random-util.c b/src/basic/random-util.c index 589575cf00f..a8bcee18435 100644 --- a/src/basic/random-util.c +++ b/src/basic/random-util.c @@ -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; -- 2.47.3