From: Peter Jones <pjones@redhat.com>
Date: Fri, 19 Jun 2009 19:44:32 +0000 (-0400)
Subject: switch_root: do recursiveRemove after our root is moved to avoid races.
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2a7ccc65e998fb5b5ad679866730bcdbfc2c1f88;p=util-linux

switch_root: do recursiveRemove after our root is moved to avoid races.

This way there's no race between unlinking the /newroot directory and
the MS_MOVE/chroot() to get away from it.

Signed-off-by: Peter Jones <pjones@redhat.com>
---

diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
index 1de3a2e5..b947f544 100644
--- a/sys-utils/switch_root.c
+++ b/sys-utils/switch_root.c
@@ -135,15 +135,6 @@ static int switchroot(const char *newroot)
 	}
 
 	cfd = open("/", O_RDONLY);
-	if (cfd >= 0) {
-		pid = fork();
-		if (pid <= 0) {
-			recursiveRemove(cfd);
-			if (pid == 0)
-				exit(EXIT_SUCCESS);
-		}
-		close(cfd);
-	}
 
 	if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
 		warn("failed to mount moving %s to /", newroot);
@@ -154,6 +145,16 @@ static int switchroot(const char *newroot)
 		warn("failed to change root");
 		return -1;
 	}
+
+	if (cfd >= 0) {
+		pid = fork();
+		if (pid <= 0) {
+			recursiveRemove(cfd);
+			if (pid == 0)
+				exit(EXIT_SUCCESS);
+		}
+		close(cfd);
+	}
 	return 0;
 }