FAILED: patch "[PATCH] ubifs: Fix memleak when insert_old_idx() failed" failed to apply to 4.14-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y
git checkout FETCH_HEAD
git cherry-pick -x b5fda08ef213352ac2df7447611eb4d383cce929
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023050610-devourer-bobble-44fa@gregkh' --subject-prefix 'PATCH 4.14.y' HEAD^..

Possible dependencies:

b5fda08ef213 ("ubifs: Fix memleak when insert_old_idx() failed")
7d01cb27f6ae ("Revert "ubifs: dirty_cow_znode: Fix memleak in error handling path"")
122deabfe142 ("ubifs: dirty_cow_znode: Fix memleak in error handling path")
6eb61d587f45 ("ubifs: Pass struct ubifs_info to ubifs_assert()")
0c1ad5242d4f ("ubifs: switch to fscrypt_prepare_rename()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b5fda08ef213352ac2df7447611eb4d383cce929 Mon Sep 17 00:00:00 2001
From: Zhihao Cheng <chengzhihao1@huawei.com>
Date: Wed, 1 Mar 2023 20:29:19 +0800
Subject: [PATCH] ubifs: Fix memleak when insert_old_idx() failed

Following process will cause a memleak for copied up znode:

dirty_cow_znode
  zn = copy_znode(c, znode);
  err = insert_old_idx(c, zbr->lnum, zbr->offs);
  if (unlikely(err))
     return ERR_PTR(err);   // No one refers to zn.

Fetch a reproducer in [Link].

Function copy_znode() is split into 2 parts: resource allocation
and znode replacement, insert_old_idx() is split in similar way,
so resource cleanup could be done in error handling path without
corrupting metadata(mem & disk).
It's okay that old index inserting is put behind of add_idx_dirt(),
old index is used in layout_leb_in_gaps(), so the two processes do
not depend on each other.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216705
Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Cc: stable@vger.kernel.org
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 2df56bbc6865..6b7d95b65f4b 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -44,6 +44,33 @@ enum {
 	NOT_ON_MEDIA = 3,
 };
 
+static void do_insert_old_idx(struct ubifs_info *c,
+			      struct ubifs_old_idx *old_idx)
+{
+	struct ubifs_old_idx *o;
+	struct rb_node **p, *parent = NULL;
+
+	p = &c->old_idx.rb_node;
+	while (*p) {
+		parent = *p;
+		o = rb_entry(parent, struct ubifs_old_idx, rb);
+		if (old_idx->lnum < o->lnum)
+			p = &(*p)->rb_left;
+		else if (old_idx->lnum > o->lnum)
+			p = &(*p)->rb_right;
+		else if (old_idx->offs < o->offs)
+			p = &(*p)->rb_left;
+		else if (old_idx->offs > o->offs)
+			p = &(*p)->rb_right;
+		else {
+			ubifs_err(c, "old idx added twice!");
+			kfree(old_idx);
+		}
+	}
+	rb_link_node(&old_idx->rb, parent, p);
+	rb_insert_color(&old_idx->rb, &c->old_idx);
+}
+
 /**
  * insert_old_idx - record an index node obsoleted since the last commit start.
  * @c: UBIFS file-system description object
@@ -69,35 +96,15 @@ enum {
  */
 static int insert_old_idx(struct ubifs_info *c, int lnum, int offs)
 {
-	struct ubifs_old_idx *old_idx, *o;
-	struct rb_node **p, *parent = NULL;
+	struct ubifs_old_idx *old_idx;
 
 	old_idx = kmalloc(sizeof(struct ubifs_old_idx), GFP_NOFS);
 	if (unlikely(!old_idx))
 		return -ENOMEM;
 	old_idx->lnum = lnum;
 	old_idx->offs = offs;
+	do_insert_old_idx(c, old_idx);
 
-	p = &c->old_idx.rb_node;
-	while (*p) {
-		parent = *p;
-		o = rb_entry(parent, struct ubifs_old_idx, rb);
-		if (lnum < o->lnum)
-			p = &(*p)->rb_left;
-		else if (lnum > o->lnum)
-			p = &(*p)->rb_right;
-		else if (offs < o->offs)
-			p = &(*p)->rb_left;
-		else if (offs > o->offs)
-			p = &(*p)->rb_right;
-		else {
-			ubifs_err(c, "old idx added twice!");
-			kfree(old_idx);
-			return 0;
-		}
-	}
-	rb_link_node(&old_idx->rb, parent, p);
-	rb_insert_color(&old_idx->rb, &c->old_idx);
 	return 0;
 }
 
@@ -199,23 +206,6 @@ static struct ubifs_znode *copy_znode(struct ubifs_info *c,
 	__set_bit(DIRTY_ZNODE, &zn->flags);
 	__clear_bit(COW_ZNODE, &zn->flags);
 
-	ubifs_assert(c, !ubifs_zn_obsolete(znode));
-	__set_bit(OBSOLETE_ZNODE, &znode->flags);
-
-	if (znode->level != 0) {
-		int i;
-		const int n = zn->child_cnt;
-
-		/* The children now have new parent */
-		for (i = 0; i < n; i++) {
-			struct ubifs_zbranch *zbr = &zn->zbranch[i];
-
-			if (zbr->znode)
-				zbr->znode->parent = zn;
-		}
-	}
-
-	atomic_long_inc(&c->dirty_zn_cnt);
 	return zn;
 }
 
@@ -233,6 +223,42 @@ static int add_idx_dirt(struct ubifs_info *c, int lnum, int dirt)
 	return ubifs_add_dirt(c, lnum, dirt);
 }
 
+/**
+ * replace_znode - replace old znode with new znode.
+ * @c: UBIFS file-system description object
+ * @new_zn: new znode
+ * @old_zn: old znode
+ * @zbr: the branch of parent znode
+ *
+ * Replace old znode with new znode in TNC.
+ */
+static void replace_znode(struct ubifs_info *c, struct ubifs_znode *new_zn,
+			  struct ubifs_znode *old_zn, struct ubifs_zbranch *zbr)
+{
+	ubifs_assert(c, !ubifs_zn_obsolete(old_zn));
+	__set_bit(OBSOLETE_ZNODE, &old_zn->flags);
+
+	if (old_zn->level != 0) {
+		int i;
+		const int n = new_zn->child_cnt;
+
+		/* The children now have new parent */
+		for (i = 0; i < n; i++) {
+			struct ubifs_zbranch *child = &new_zn->zbranch[i];
+
+			if (child->znode)
+				child->znode->parent = new_zn;
+		}
+	}
+
+	zbr->znode = new_zn;
+	zbr->lnum = 0;
+	zbr->offs = 0;
+	zbr->len = 0;
+
+	atomic_long_inc(&c->dirty_zn_cnt);
+}
+
 /**
  * dirty_cow_znode - ensure a znode is not being committed.
  * @c: UBIFS file-system description object
@@ -265,21 +291,32 @@ static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
 		return zn;
 
 	if (zbr->len) {
-		err = insert_old_idx(c, zbr->lnum, zbr->offs);
-		if (unlikely(err))
-			return ERR_PTR(err);
+		struct ubifs_old_idx *old_idx;
+
+		old_idx = kmalloc(sizeof(struct ubifs_old_idx), GFP_NOFS);
+		if (unlikely(!old_idx)) {
+			err = -ENOMEM;
+			goto out;
+		}
+		old_idx->lnum = zbr->lnum;
+		old_idx->offs = zbr->offs;
+
 		err = add_idx_dirt(c, zbr->lnum, zbr->len);
-	} else
-		err = 0;
+		if (err) {
+			kfree(old_idx);
+			goto out;
+		}
 
-	zbr->znode = zn;
-	zbr->lnum = 0;
-	zbr->offs = 0;
-	zbr->len = 0;
+		do_insert_old_idx(c, old_idx);
+	}
+
+	replace_znode(c, zn, znode, zbr);
 
-	if (unlikely(err))
-		return ERR_PTR(err);
 	return zn;
+
+out:
+	kfree(zn);
+	return ERR_PTR(err);
 }
 
 /**