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From:   Bragatheswaran Manickavel <bragathemanick0908@gmail.com>
To:     clm@fb.com, josef@toxicpanda.com, dsterba@suse.com
Cc:     Bragatheswaran Manickavel <bragathemanick0908@gmail.com>,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzbot+d66de4cbf532749df35f@syzkaller.appspotmail.com
Subject: [PATCH v2] btrfs: ref-verify: fix memory leaks
Date:   Sat, 18 Nov 2023 14:40:12 +0530
Message-Id: <20231118091012.14818-1-bragathemanick0908@gmail.com>
MIME-Version: 1.0
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Precedence: bulk

In btrfs_ref_tree_mod(), when !parent 're' was allocated
through kmalloc(). In the following code, if an error occurs,
the execution will be redirected to 'out' or 'out_unlock' and
the function will be exited. However, on some of the paths,
're' are not deallocated and may lead to memory leaks.

For example : lookup_block_entry() for 'be' returns null, the
out label will be invoked. During that flow ref and ra was
freed but not re, which can potentially lead to memleak

Reported-and-tested-by: syzbot+d66de4cbf532749df35f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d66de4cbf532749df35f
Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@gmail.com>
---
V1 -> V2: 're' shouldn't be freed after it added to rbtree

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

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 1f62976bee82..6486f0d7e993 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -794,6 +794,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 			dump_ref_action(fs_info, ra);
 			kfree(ref);
 			kfree(ra);
+			kfree(re);
 			goto out_unlock;
 		} else if (be->num_refs == 0) {
 			btrfs_err(fs_info,
@@ -803,6 +804,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 			dump_ref_action(fs_info, ra);
 			kfree(ref);
 			kfree(ra);
+			kfree(re);
 			goto out_unlock;
 		}
 
-- 
2.34.1