Patch "ubifs: dirty_cow_znode: Fix memleak in error handling path" has been added to the 4.14-stable tree

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This is a note to let you know that I've just added the patch titled

    ubifs: dirty_cow_znode: Fix memleak in error handling path

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ubifs-dirty_cow_znode-fix-memleak-in-error-handling-.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit eb4fbeae21f34fb06ac6934a1111adfc79f4198c
Author: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Date:   Fri Nov 18 17:02:36 2022 +0800

    ubifs: dirty_cow_znode: Fix memleak in error handling path
    
    [ Upstream commit 122deabfe1428bffe95e2bf364ff8a5059bdf089 ]
    
    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.
    
    Fix it by adding copied znode back to tnc, then it will be freed
    by ubifs_destroy_tnc_subtree() while closing tnc.
    
    Fetch a reproducer in [Link].
    
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=216705
    Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
    Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
    Signed-off-by: Richard Weinberger <richard@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 20b70e178c4fa..6c4af1cfce346 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -279,11 +279,18 @@ static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
 	if (zbr->len) {
 		err = insert_old_idx(c, zbr->lnum, zbr->offs);
 		if (unlikely(err))
-			return ERR_PTR(err);
+			/*
+			 * Obsolete znodes will be freed by tnc_destroy_cnext()
+			 * or free_obsolete_znodes(), copied up znodes should
+			 * be added back to tnc and freed by
+			 * ubifs_destroy_tnc_subtree().
+			 */
+			goto out;
 		err = add_idx_dirt(c, zbr->lnum, zbr->len);
 	} else
 		err = 0;
 
+out:
 	zbr->znode = zn;
 	zbr->lnum = 0;
 	zbr->offs = 0;



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