From: Thomas Deutschmann <whissi@gentoo.org>
Date: Mon, 8 Feb 2021 14:30:25 +0000 (+0100)
Subject: switch_root: check if mount point to move even exists
X-Git-Tag: v2.36.2~12
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=65d9baa10feaaa7752601c5846bdc2de70fe8a83;p=thirdparty%2Futil-linux.git

switch_root: check if mount point to move even exists

Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>
---

diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
index a42bceca31..0176690401 100644
--- a/sys-utils/switch_root.c
+++ b/sys-utils/switch_root.c
@@ -131,7 +131,12 @@ static int switchroot(const char *newroot)
 	int i;
 	int cfd;
 	pid_t pid;
-	struct stat newroot_stat, sb;
+	struct stat newroot_stat, oldroot_stat, sb;
+
+	if (stat("/", &oldroot_stat) != 0) {
+		warn(_("stat of %s failed"), "/");
+		return -1;
+	}
 
 	if (stat(newroot, &newroot_stat) != 0) {
 		warn(_("stat of %s failed"), newroot);
@@ -143,6 +148,11 @@ static int switchroot(const char *newroot)
 
 		snprintf(newmount, sizeof(newmount), "%s%s", newroot, umounts[i]);
 
+		if ((stat(umounts[i], &sb) == 0) && sb.st_dev == oldroot_stat.st_dev) {
+			/* mount point to move seems to be a normal directory or stat failed */
+			continue;
+		}
+
 		if ((stat(newmount, &sb) != 0) || (sb.st_dev != newroot_stat.st_dev)) {
 			/* mount point seems to be mounted already or stat failed */
 			umount2(umounts[i], MNT_DETACH);