https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277906
Bug ID: 277906
Summary: libalias fails to report an error from dlsym()
Product: Base System
Version: 14.0-RELEASE
Hardware: Any
OS: Any
Status: New
Severity: Affects Some People
Priority: ---
Component: misc
Assignee: b...@freebsd.org
Reporter: igor.gusa...@kaspersky.com
The following code can be found in file /usr/src/sys/netinet/libalias/aliasc
around line 1715
p = dlsym(handle, "alias_mod");
if ((error = dlerror()) != NULL) {
fprintf(stderr, "%s\n", dlerror());
return (EINVAL);
}
This code calls dlerror() function twice: first time to check if there is an
error, and the second time to print that error. Such approach is wrong, as
described in manual page for dlerror(3):
> At each call
> to dlerror(), the error indication is reset. Thus in the case of two
> calls to dlerror(), where the second call follows the first immediately,
> the second call will always return a null pointer.
Which may result in the following not helpful error message when trying to
start natd:
# service natd restart
Stopping natd.
Waiting for PIDS: 23950.
Starting natd.
(null) <--- Here. This null message is printed at
alias.c:1715
#
Suggested fix:
Apply the following patch to /usr/src/sys/netinet/libalias/alias.c
--- alias.c 2023-11-10 03:07:53.000000000 +0300
+++ alias.c.new 2024-03-23 15:48:15.335314000 +0300
@@ -1712,7 +1712,7 @@
p = dlsym(handle, "alias_mod");
if ((error = dlerror()) != NULL) {
- fprintf(stderr, "%s\n", dlerror());
+ fprintf(stderr, "%s\n", error);
return (EINVAL);
}
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