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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Wenwen Wang <wenwen@cs.uga.edu>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 5.5 22/80] btrfs: ref-verify: fix memory leaks
Date:   Tue, 18 Feb 2020 20:54:43 +0100
Message-Id: <20200218190434.459046517@linuxfoundation.org>
In-Reply-To: <20200218190432.043414522@linuxfoundation.org>
References: <20200218190432.043414522@linuxfoundation.org>
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From: Wenwen Wang <wenwen@cs.uga.edu>

commit f311ade3a7adf31658ed882aaab9f9879fdccef7 upstream.

In btrfs_ref_tree_mod(), 'ref' and 'ra' are allocated through kzalloc() and
kmalloc(), respectively. 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, 'ref' and 'ra' are not
deallocated, leading to memory leaks. For example, if 'action' is
BTRFS_ADD_DELAYED_EXTENT, add_block_entry() will be invoked. If the return
value indicates an error, the execution will be redirected to 'out'. But,
'ref' is not deallocated on this path, causing a memory leak.

To fix the above issues, deallocate both 'ref' and 'ra' before exiting from
the function when an error is encountered.

CC: stable@vger.kernel.org # 4.15+
Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/ref-verify.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -744,6 +744,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_i
 		 */
 		be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
 		if (IS_ERR(be)) {
+			kfree(ref);
 			kfree(ra);
 			ret = PTR_ERR(be);
 			goto out;
@@ -757,6 +758,8 @@ int btrfs_ref_tree_mod(struct btrfs_fs_i
 			"re-allocated a block that still has references to it!");
 			dump_block_entry(fs_info, be);
 			dump_ref_action(fs_info, ra);
+			kfree(ref);
+			kfree(ra);
 			goto out_unlock;
 		}
 
@@ -819,6 +822,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_i
 "dropping a ref for a existing root that doesn't have a ref on the block");
 				dump_block_entry(fs_info, be);
 				dump_ref_action(fs_info, ra);
+				kfree(ref);
 				kfree(ra);
 				goto out_unlock;
 			}
@@ -834,6 +838,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_i
 "attempting to add another ref for an existing ref on a tree block");
 			dump_block_entry(fs_info, be);
 			dump_ref_action(fs_info, ra);
+			kfree(ref);
 			kfree(ra);
 			goto out_unlock;
 		}