From: Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>
Date: Wed, 10 Jun 2026 13:28:48 +0000 (+0200)
Subject: nsenter: Fix invalid fd check in enter_namespaces
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=40449fc62d803917bdee0908eab2f174065c5cf9;p=thirdparty%2Futil-linux.git

nsenter: Fix invalid fd check in enter_namespaces

When nsenter is executed with closed stdin, one pid_fd will be 0,
which is a valid file descriptor. But with current code namespace switch
is skipped, leading to incorrect results.

Fixes: f18be0ca5aa7 ("nsenter: use pidfd to enter target namespaces")
Signed-off-by: Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>
---

diff --git a/sys-utils/nsenter.c b/sys-utils/nsenter.c
index b10c5773f..c1706cef9 100644
--- a/sys-utils/nsenter.c
+++ b/sys-utils/nsenter.c
@@ -356,7 +356,7 @@ static void enter_namespaces(int pid_fd, int namespaces, bool ignore_errors)
 {
 	struct namespace_file *n =  NULL;
 
-	if (pid_fd) {
+	if (pid_fd >= 0) {
 		int ns = 0;
 		while ((n = next_enabled_nsfile(n, namespaces))) {
 			if (n->fd < 0)