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/cfgparse-ssl.c b/src/cfgparse-ssl.c
index 7acd135..462743e 100644
--- a/src/cfgparse-ssl.c
+++ b/src/cfgparse-ssl.c
@@ -659,11 +659,11 @@
}
if ((*args[cur_arg + 1] != '/' ) && global_ssl.crt_base) {
- if ((strlen(global_ssl.crt_base) + 1 + strlen(args[cur_arg + 1]) + 1) > MAXPATHLEN) {
+ if ((strlen(global_ssl.crt_base) + 1 + strlen(args[cur_arg + 1]) + 1) > sizeof(path) ||
+ snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, args[cur_arg + 1]) > sizeof(path)) {
memprintf(err, "'%s' : path too long", args[cur_arg]);
return ERR_ALERT | ERR_FATAL;
}
- snprintf(path, sizeof(path), "%s/%s", global_ssl.crt_base, args[cur_arg + 1]);
return ssl_sock_load_cert(path, conf, err);
}