BUILD: ssl: work around bogus warning in gcc 12's -Wformat-truncation
As was first reported by Ilya in issue #1513, Gcc 12 incorrectly reports
a possible overflow from the concatenation of two strings whose size was
previously checked to fit:
src/ssl_crtlist.c: In function 'crtlist_parse_file':
src/ssl_crtlist.c:545:58: error: '%s' directive output may be truncated writing up to 4095 bytes into a region of size between 1 and 4096 [-Werror=format-truncation=]
545 | snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, crt_path);
| ^~
src/ssl_crtlist.c:545:25: note: 'snprintf' output between 2 and 8192 bytes into a destination of size 4097
545 | snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, crt_path);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It would be a bit concerning to disable -Wformat-truncation because it
might detect real programming mistakes at other places. The solution
adopted in this patch is absolutely ugly and error-prone, but it works,
it consists in integrating the snprintf() call in the error condition
and to test the result again. Let's hope a smarter compiler will not
warn that this test is absurd since guaranteed by the first condition...
This may have to be backported for those suffering from a compiler upgrade.
diff --git a/src/ssl_crtlist.c b/src/ssl_crtlist.c
index 1615ac5..f43982f 100644
--- a/src/ssl_crtlist.c
+++ b/src/ssl_crtlist.c
@@ -536,13 +536,13 @@
}
if (*crt_path != '/' && global_ssl.crt_base) {
- if ((strlen(global_ssl.crt_base) + 1 + strlen(crt_path)) > MAXPATHLEN) {
+ if ((strlen(global_ssl.crt_base) + 1 + strlen(crt_path)) > sizeof(path) ||
+ snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, crt_path)) {
memprintf(err, "parsing [%s:%d]: '%s' : path too long",
file, linenum, crt_path);
cfgerr |= ERR_ALERT | ERR_FATAL;
goto error;
}
- snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, crt_path);
crt_path = path;
}
@@ -1270,12 +1270,12 @@
}
if (*cert_path != '/' && global_ssl.crt_base) {
- if ((strlen(global_ssl.crt_base) + 1 + strlen(cert_path)) > MAXPATHLEN) {
+ if ((strlen(global_ssl.crt_base) + 1 + strlen(cert_path)) > sizeof(path) ||
+ snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, cert_path) > sizeof(path)) {
memprintf(&err, "'%s' : path too long", cert_path);
cfgerr |= ERR_ALERT | ERR_FATAL;
goto error;
}
- snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, cert_path);
cert_path = path;
}