[hackers] [ubase][PATCH] pidof: fix -o option being applied without -o flag (and correct exit code)

From: runitclean <runitclean_AT_disroot.org>
Date: Wed, 17 Dec 2025 12:39:17 +0100

The omit PID list was parsed even when -o was not specified.
In that case, arg was left uninitialized, so passing it to strtok()
resulted in undefined behavior and could lead to a segfault.

Only parse omit PIDs when -o is set.

also fix the exit status to return 1 when no matching PID is found

---
 pidof.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/pidof.c b/pidof.c
index c98bf92..355b011 100644
--- a/pidof.c
+++ b/pidof.c
_AT_@ -55,13 +55,15 @@ main(int argc, char *argv[])
 
 	SLIST_INIT(&omitpid_head);
 
-	for (p = strtok(arg, ","); p; p = strtok(NULL, ",")) {
-		pe = emalloc(sizeof(*pe));
-		if (strcmp(p, "%PPID") == 0)
-			pe->pid = getppid();
-		else
-			pe->pid = estrtol(p, 10);
-		SLIST_INSERT_HEAD(&omitpid_head, pe, entry);
+	if (oflag) {
+		for (p = strtok(arg, ","); p; p = strtok(NULL, ",")) {
+			pe = emalloc(sizeof(*pe));
+			if (strcmp(p, "%PPID") == 0)
+				pe->pid = getppid();
+			else
+				pe->pid = estrtol(p, 10);
+			SLIST_INSERT_HEAD(&omitpid_head, pe, entry);
+		}
 	}
 
 	if (!(dp = opendir("/proc")))
_AT_@ -110,5 +112,5 @@ out:
 
 	closedir(dp);
 
-	return 0;
+	return found ? 0 : 1;
 }
-- 
2.51.0

Received on Wed Dec 17 2025 - 12:39:17 CET