From: Karel Zak <kzak@redhat.com>
Date: Mon, 22 Apr 2024 11:09:04 +0000 (+0200)
Subject: libmount: Fix access check for utab in context
X-Git-Tag: v2.42-start~384^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=97f7bfc0fdf74b6a6e220ba9d2f620386e660b29;p=thirdparty%2Futil-linux.git

libmount: Fix access check for utab in context

The function mnt_has_regular_utab() properly detects that the utab is
not writable, but this is ignored by the high-level context API. As a
result, the library later attempts to update the file and ends up with
a warning in mount(8):

 $ mkdir sys
 $ unshare --map-root-user --mount
 $ mount --rbind /sys sys
 $ umount --lazy sys; echo $?
 umount: /home/user/sys: filesystem was unmounted, but failed to update userspace mount table.
 16

In this case, the utab should be ignored.

Fixes: https://github.com/util-linux/util-linux/issues/2981
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 952287a26..5206c1d58 100644
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -367,8 +367,7 @@ const char *mnt_context_get_writable_tabpath(struct libmnt_context *cxt)
 {
 	assert(cxt);
 
-	context_init_paths(cxt, 1);
-	return cxt->utab_path;
+	return mnt_context_utab_writable(cxt) ? cxt->utab_path : NULL;
 }