btrfs: ref-verify: fix memory leaks in btrfs_ref_tree_mod()

commit f91192cd68591c6b037da345bc9fcd5e50540358 upstream.

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' are freed but not 're',
which can potentially lead to a memory leak.

CC: stable@vger.kernel.org # 5.10+
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>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 95d2849..e646662 100644 (file)
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -791,6 +791,7 @@ 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,
@@ -800,6 +801,7 @@ 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;
                }