linux-kernel - [PATCH 5.4 012/152] btrfs: ref-verify: fix memory leak in add_block

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Message-Id: <20200820091554.266984251@linuxfoundation.org>
Date:   Thu, 20 Aug 2020 11:19:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Rix <trix@...hat.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 5.4 012/152] btrfs: ref-verify: fix memory leak in add_block_entry

From: Tom Rix <trix@...hat.com>

commit d60ba8de1164e1b42e296ff270c622a070ef8fe7 upstream.

clang static analysis flags this error

fs/btrfs/ref-verify.c:290:3: warning: Potential leak of memory pointed to by 're' [unix.Malloc]
                kfree(be);
                ^~~~~

The problem is in this block of code:

	if (root_objectid) {
		struct root_entry *exist_re;

		exist_re = insert_root_entry(&exist->roots, re);
		if (exist_re)
			kfree(re);
	}

There is no 'else' block freeing when root_objectid is 0. Add the
missing kfree to the else branch.

Fixes: fd708b81d972 ("Btrfs: add a extent ref verify tool")
CC: stable@...r.kernel.org # 4.19+
Signed-off-by: Tom Rix <trix@...hat.com>
Reviewed-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/btrfs/ref-verify.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -286,6 +286,8 @@ static struct block_entry *add_block_ent
 			exist_re = insert_root_entry(&exist->roots, re);
 			if (exist_re)
 				kfree(re);
+		} else {
+			kfree(re);
 		}
 		kfree(be);
 		return exist;