From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Wed, 5 May 2021 09:24:36 +0000 (+0200)
Subject: 4.19-stable patches
X-Git-Tag: v4.19.190~10
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=af0e9f88e27e8151db79b25ad1ac6c21775b9833;p=thirdparty%2Fkernel%2Fstable-queue.git

4.19-stable patches

added patches:
	ovl-allow-upperdir-inside-lowerdir.patch
---

diff --git a/queue-4.19/ovl-allow-upperdir-inside-lowerdir.patch b/queue-4.19/ovl-allow-upperdir-inside-lowerdir.patch
new file mode 100644
index 00000000000..353d5415107
--- /dev/null
+++ b/queue-4.19/ovl-allow-upperdir-inside-lowerdir.patch
@@ -0,0 +1,83 @@
+From 708fa01597fa002599756bf56a96d0de1677375c Mon Sep 17 00:00:00 2001
+From: Miklos Szeredi <mszeredi@redhat.com>
+Date: Mon, 12 Apr 2021 12:00:37 +0200
+Subject: ovl: allow upperdir inside lowerdir
+
+From: Miklos Szeredi <mszeredi@redhat.com>
+
+commit 708fa01597fa002599756bf56a96d0de1677375c upstream.
+
+Commit 146d62e5a586 ("ovl: detect overlapping layers") made sure we don't
+have overlapping layers, but it also broke the arguably valid use case of
+
+ mount -olowerdir=/,upperdir=/subdir,..
+
+where upperdir overlaps lowerdir on the same filesystem.  This has been
+causing regressions.
+
+Revert the check, but only for the specific case where upperdir and/or
+workdir are subdirectories of lowerdir.  Any other overlap (e.g. lowerdir
+is subdirectory of upperdir, etc) case is crazy, so leave the check in
+place for those.
+
+Overlaps are detected at lookup time too, so reverting the mount time check
+should be safe.
+
+Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
+Cc: <stable@vger.kernel.org> # v5.2
+Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/overlayfs/super.c |   12 +++++++-----
+ 1 file changed, 7 insertions(+), 5 deletions(-)
+
+--- a/fs/overlayfs/super.c
++++ b/fs/overlayfs/super.c
+@@ -1479,7 +1479,8 @@ out_err:
+  * - upper/work dir of any overlayfs instance
+  */
+ static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
+-			   struct dentry *dentry, const char *name)
++			   struct dentry *dentry, const char *name,
++			   bool is_lower)
+ {
+ 	struct dentry *next = dentry, *parent;
+ 	int err = 0;
+@@ -1491,7 +1492,7 @@ static int ovl_check_layer(struct super_
+ 
+ 	/* Walk back ancestors to root (inclusive) looking for traps */
+ 	while (!err && parent != next) {
+-		if (ovl_lookup_trap_inode(sb, parent)) {
++		if (is_lower && ovl_lookup_trap_inode(sb, parent)) {
+ 			err = -ELOOP;
+ 			pr_err("overlayfs: overlapping %s path\n", name);
+ 		} else if (ovl_is_inuse(parent)) {
+@@ -1517,7 +1518,7 @@ static int ovl_check_overlapping_layers(
+ 
+ 	if (ofs->upper_mnt) {
+ 		err = ovl_check_layer(sb, ofs, ofs->upper_mnt->mnt_root,
+-				      "upperdir");
++				      "upperdir", false);
+ 		if (err)
+ 			return err;
+ 
+@@ -1528,7 +1529,8 @@ static int ovl_check_overlapping_layers(
+ 		 * workbasedir.  In that case, we already have their traps in
+ 		 * inode cache and we will catch that case on lookup.
+ 		 */
+-		err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir");
++		err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir",
++				      false);
+ 		if (err)
+ 			return err;
+ 	}
+@@ -1536,7 +1538,7 @@ static int ovl_check_overlapping_layers(
+ 	for (i = 0; i < ofs->numlower; i++) {
+ 		err = ovl_check_layer(sb, ofs,
+ 				      ofs->lower_layers[i].mnt->mnt_root,
+-				      "lowerdir");
++				      "lowerdir", true);
+ 		if (err)
+ 			return err;
+ 	}
diff --git a/queue-4.19/series b/queue-4.19/series
index 705e7eecdaa..88aab2a175e 100644
--- a/queue-4.19/series
+++ b/queue-4.19/series
@@ -12,3 +12,4 @@ usb-add-reset-resume-quirk-for-wd19-s-realtek-hub.patch
 asoc-ak4458-add-module_device_table.patch
 asoc-ak5558-add-module_device_table.patch
 platform-x86-thinkpad_acpi-correct-thermal-sensor-allocation.patch
+ovl-allow-upperdir-inside-lowerdir.patch