ext4: fix possible use after free in ext4_quota_enable
commit 61157b24e60fb3cd1f85f2c76a7b1d628f970144 upstream.
The function frees qf_inode via iput but then pass qf_inode to
lockdep_set_quota_inode on the failure path. This may result in a
use-after-free bug. The patch frees df_inode only when it is never used.
Fixes: daf647d2dd5 ("ext4: add lockdep annotations for i_data_sem")
Cc: stable@kernel.org # 4.6
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 75177eb..67d9e3c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5425,9 +5425,9 @@
qf_inode->i_flags |= S_NOQUOTA;
lockdep_set_quota_inode(qf_inode, I_DATA_SEM_QUOTA);
err = dquot_enable(qf_inode, type, format_id, flags);
- iput(qf_inode);
if (err)
lockdep_set_quota_inode(qf_inode, I_DATA_SEM_NORMAL);
+ iput(qf_inode);
return err;
}