From d2abde53033d58b6665becd75f854ad87aba33f6 Mon Sep 17 00:00:00 2001 From: Leah Rowe Date: Tue, 31 Mar 2026 15:43:43 +0100 Subject: libreboot-utils: stricter errno handling where possible, try not to clobber sys errno. override it only when relatively safe. also: when a syscall succeeds, it may set errno. this is rare, but permitted (nothing specified against it in specs, and the specs say that errno is undefined on success). i'm not libc, but i'm wrapping around it, so i need to be careful in how i handle the errno value. also: i removed the requirement for directories to be executable, in mkhtemp.c, because this isn't required and will only break certain setups. in world_writeable and sticky, i made the checks stricter: the faccessat check was being skipped on some paths, so i've closed that loophole now. i also generally cleaned up some code, as part of the errno handling refactoring, where it made sense to do so, plus a few other bits of code cleanup. Signed-off-by: Leah Rowe --- util/libreboot-utils/lib/string.c | 54 +++++++++++++++++++++++++-------------- 1 file changed, 35 insertions(+), 19 deletions(-) (limited to 'util/libreboot-utils/lib/string.c') diff --git a/util/libreboot-utils/lib/string.c b/util/libreboot-utils/lib/string.c index ad11d29d..ce54a524 100644 --- a/util/libreboot-utils/lib/string.c +++ b/util/libreboot-utils/lib/string.c @@ -50,6 +50,7 @@ pagesize(void) { static long rval = 0; static int set = 0; + int saved_errno = 0; if (!set) { if ((rval = sysconf(_SC_PAGESIZE)) < 0) @@ -57,6 +58,7 @@ pagesize(void) set = 1; } + reset_caller_errno(0); return rval; } @@ -92,7 +94,9 @@ smalloc(char **buf, size_t size) void * vmalloc(void **buf, size_t size) { + int saved_errno = errno; void *rval = NULL; + errno = 0; if (size >= SIZE_MAX - 1) err_exit(EOVERFLOW, "integer overflow in vmalloc"); @@ -116,6 +120,7 @@ vmalloc(void **buf, size_t size) if ((rval = malloc(size)) == NULL) err_exit(errno, "malloc fail in vmalloc"); + reset_caller_errno(0); return *buf = rval; } @@ -131,6 +136,7 @@ scmp(const char *a, size_t wa; size_t wb; int saved_errno = errno; + errno = 0; if (if_err(a == NULL || b == NULL || rval == NULL, EFAULT)) goto err; @@ -171,14 +177,14 @@ scmp(const char *a, goto out; err: - (void) set_errno(saved_errno, EFAULT); + (void) with_fallback_errno(EFAULT); if (rval != NULL) *rval = -1; err_exit(errno, "scmp"); return -1; out: - errno = saved_errno; + reset_caller_errno(0); return *rval; } @@ -215,13 +221,14 @@ slen(const char *s, size_t i = 0; size_t w; size_t j; + errno = 0; if (if_err(s == NULL || rval == NULL, EFAULT)) goto err; for ( ; ((uintptr_t)(s + i) % sizeof(size_t)) != 0; i++) { - if (i >= maxlen) + if (if_err(i >= maxlen, EOVERFLOW)) goto err; if (s[i] == '\0') { *rval = i; @@ -252,14 +259,14 @@ slen(const char *s, } err: - (void) set_errno(saved_errno, EFAULT); + (void) with_fallback_errno(EFAULT); if (rval != NULL) *rval = 0; err_exit(errno, "slen"); /* abort */ return 0; /* gcc15 is happy */ out: - errno = saved_errno; + reset_caller_errno(0); return *rval; } @@ -273,6 +280,7 @@ sdup(const char *s, size_t i = 0; char *out = NULL; int saved_errno = errno; + errno = 0; if (if_err(dest == NULL || *dest != NULL || s == NULL, EFAULT)) goto err; @@ -326,12 +334,12 @@ err: if (dest != NULL) *dest = NULL; - (void) set_errno(saved_errno, EFAULT); + (void) with_fallback_errno(EFAULT); err_exit(errno, "sdup"); return NULL; out: - errno = saved_errno; + reset_caller_errno(0); return *dest; } @@ -345,6 +353,7 @@ scatn(ssize_t sc, const char **sv, char *rcur = NULL; char *rtmp = NULL; size_t i; + errno = 0; if (if_err(sc < 2, EINVAL) || if_err(sv == NULL, EFAULT) || @@ -368,7 +377,7 @@ scatn(ssize_t sc, const char **sv, rtmp = NULL; } - errno = saved_errno; + reset_caller_errno(0); *rval = final; return *rval; err: @@ -376,7 +385,7 @@ err: free_and_set_null(&rtmp); free_and_set_null(&final); - (void) set_errno(saved_errno, EFAULT); + (void) with_fallback_errno(EFAULT); err_exit(errno, "scatn"); return NULL; @@ -391,6 +400,7 @@ scat(const char *s1, const char *s2, size_t size2; char *rval = NULL; int saved_errno = errno; + errno = 0; if (if_err(dest == NULL || *dest != NULL, EFAULT)) goto err; @@ -408,11 +418,11 @@ scat(const char *s1, const char *s2, memcpy(rval + size1, s2, size2); *(rval + size1 + size2) = '\0'; + reset_caller_errno(0); *dest = rval; - errno = saved_errno; return *dest; err: - (void) set_errno(saved_errno, EINVAL); + (void) with_fallback_errno(EINVAL); if (dest != NULL) *dest = NULL; err_exit(errno, "scat"); @@ -431,6 +441,7 @@ dcat(const char *s, size_t n, char *rval1 = NULL; char *rval2 = NULL; int saved_errno = errno; + errno = 0; if (if_err(dest1 == NULL || dest2 == NULL, EFAULT)) goto err; @@ -450,7 +461,7 @@ dcat(const char *s, size_t n, *dest1 = rval1; *dest2 = rval2; - errno = saved_errno; + reset_caller_errno(0); return; err: @@ -459,7 +470,7 @@ err: free_and_set_null(&rval1); free_and_set_null(&rval2); - (void) set_errno(saved_errno, EINVAL); + (void) with_fallback_errno(EINVAL); err_exit(errno, "dcat"); } @@ -477,6 +488,7 @@ vcmp(const void *s1, const void *s2, size_t n) const unsigned char *x; const unsigned char *y; + errno = 0; if (if_err(s1 == NULL || s2 == NULL, EFAULT)) err_exit(EFAULT, "vcmp: null input"); @@ -497,7 +509,7 @@ vcmp(const void *s1, const void *s2, size_t n) if (x[i] != y[i]) return (int)x[i] - (int)y[i]; - errno = saved_errno; + reset_caller_errno(0); return 0; } @@ -507,9 +519,9 @@ vcmp(const void *s1, const void *s2, size_t n) * under error condition. */ int -set_errno(int saved_errno, int fallback) +with_fallback_errno(int fallback) { - if (errno == saved_errno) + if (!errno) errno = fallback; return -1; } @@ -525,7 +537,8 @@ err_exit(int nvm_errval, const char *msg, ...) func_t err_cleanup = errhook(NULL); err_cleanup(); - errno = saved_errno; + reset_caller_errno(0); + saved_errno = errno; if (!errno) saved_errno = errno = ECANCELED; @@ -536,6 +549,7 @@ err_exit(int nvm_errval, const char *msg, ...) vfprintf(stderr, msg, args); va_end(args); + errno = saved_errno; fprintf(stderr, ": %s\n", strerror(errno)); exit(EXIT_FAILURE); @@ -615,11 +629,12 @@ xpledgex(const char *promises, const char *execpromises) { int saved_errno = errno; (void) promises, (void) execpromises, (void) saved_errno; + errno = 0; #ifdef __OpenBSD__ if (pledge(promises, execpromises) == -1) err_exit(errno, "pledge"); #endif - errno = saved_errno; + reset_caller_errno(0); return 0; } int @@ -627,10 +642,11 @@ xunveilx(const char *path, const char *permissions) { int saved_errno = errno; (void) path, (void) permissions, (void) saved_errno; + errno = 0; #ifdef __OpenBSD__ if (pledge(promises, execpromises) == -1) err_exit(errno, "pledge"); #endif - errno = saved_errno; + reset_caller_errno(0); return 0; } -- cgit v1.2.1