diff options
| -rw-r--r-- | util/libreboot-utils/include/common.h | 2 | ||||
| -rw-r--r-- | util/libreboot-utils/lib/rand.c | 48 | ||||
| -rw-r--r-- | util/libreboot-utils/lottery.c | 42 |
3 files changed, 35 insertions, 57 deletions
diff --git a/util/libreboot-utils/include/common.h b/util/libreboot-utils/include/common.h index 0c8fbd3d..7f063a8c 100644 --- a/util/libreboot-utils/include/common.h +++ b/util/libreboot-utils/include/common.h @@ -391,7 +391,7 @@ void *rmalloc(size_t *size); /* don't ever use this */ void rset(void *buf, size_t n); void *mkrbuf(size_t n); char *mkrstr(size_t n); -int win_lottery(char **buf); +size_t rsize(size_t n); /* Helper functions for command: dump */ diff --git a/util/libreboot-utils/lib/rand.c b/util/libreboot-utils/lib/rand.c index 06d5f49e..3155eec3 100644 --- a/util/libreboot-utils/lib/rand.c +++ b/util/libreboot-utils/lib/rand.c @@ -72,43 +72,20 @@ * or your program dies. */ -int -win_lottery(char **buf) /* are u lucky? */ -{ - size_t size = 0; - int rval; - - char *s1 = rmalloc(&size); - char *s2 = rmalloc(&size); - - if (scmp(s1, s2, BUFSIZ + 1, &rval) >= 0 && - rval == 0) - rval = 1; /* winner! */ - else - rval = 0; - - (void) scat(s1, s2, BUFSIZ << 1, buf); - - free_if_null(&s1); - free_if_null(&s2); - - return rval; -} - void * rmalloc(size_t *rval) { - /* clamp rand to prevent modulo bias */ - size_t limit = SIZE_MAX - (SIZE_MAX % BUFSIZ); - - if (if_err(rval == NULL, EFAULT)) - return NULL; + return if_err(rval == NULL, EFAULT) ? + NULL : mkrstr(*rval = rsize(BUFSIZ)); +} - do { - rset(rval, sizeof(*rval)); - } while (*rval >= limit); +size_t +rsize(size_t n) +{ + size_t rval = SIZE_MAX; + for (; rval >= SIZE_MAX - (SIZE_MAX % n); rset(&rval, sizeof(rval))); - return mkrstr(*rval %= BUFSIZ); + return rval % n; } char * @@ -120,7 +97,7 @@ mkrstr(size_t n) /* emulates spkmodem-decode */ if (n == 0) err_no_cleanup(0, EPERM, "mkrbuf: zero-byte request"); - if (n == SIZE_MAX) + if (n >= SIZE_MAX - 1) err_no_cleanup(0, EOVERFLOW, "mkrbuf: overflow"); if (if_err((s = mkrbuf(n + 1)) == NULL, EFAULT)) @@ -138,11 +115,14 @@ mkrstr(size_t n) /* emulates spkmodem-decode */ void * mkrbuf(size_t n) { - void *buf; + void *buf = ""; if (n == 0) err_no_cleanup(0, EPERM, "mkrbuf: zero-byte request"); + if (n >= SIZE_MAX - 1) + err_no_cleanup(0, EOVERFLOW, "integer overflow in mkrbuf"); + if ((buf = malloc(n)) == NULL) err_no_cleanup(0, ENOMEM, "mkrbuf: malloc"); diff --git a/util/libreboot-utils/lottery.c b/util/libreboot-utils/lottery.c index 8157d7a9..dcede791 100644 --- a/util/libreboot-utils/lottery.c +++ b/util/libreboot-utils/lottery.c @@ -2,40 +2,38 @@ * Copyright (c) 2026 Leah Rowe <leah@libreboot.org> */ -#ifdef __OpenBSD__ -#include <sys/param.h> /* pledge(2) */ -#endif - #include <stdio.h> -#include <stdlib.h> +#include <string.h> + #include "include/common.h" +#define MAX_ALLOC (1 << 17) + +static int rigged(char **s); int main(int argc, char *argv[]) { - char *s1 = NULL; - int rval = 0; + char *s = "You lose!"; + int lucky = rigged(&s); -#if defined(__OpenBSD__) && defined(OpenBSD) -#if (OpenBSD) >= 509 +#ifdef __OpenBSD__ if (pledge("stdio", NULL) == -1) - err_no_cleanup(0, errno, "openbsd won it"); -#endif + err_no_cleanup(0, errno, "openbsd wins"); #endif - setvbuf(stdout, NULL, _IONBF, 0); + printf("%s\n", s); + return lucky; +} - if (win_lottery(&s1)) - rval = 1; - - if (s1 != NULL) { - printf("%s\n\n", s1); - free(s1); - } +static int +rigged(char **s) /* are u lucky? */ +{ + size_t size[2] = { rsize(MAX_ALLOC), rsize(MAX_ALLOC) }; - printf("%s\n", rval ? "You won!" : "You lose! Sorry!"); - return rval? EXIT_SUCCESS : EXIT_FAILURE; + return !(size[0] && size[0] == size[1] && size[0] <= MAX_ALLOC << 1 && + s != NULL) || memcmp(*s = mkrbuf(size[0] << 1), *s + size[0], + size[0]); }/* ( >:3 ) - /| |\ + /| |\ it could be you! / \ */ |