ext4: fix leaking sysfs kobject after failed mount

ext4_unregister_sysfs() only deletes the kobject.  The reference to it
needs to be put separately, like ext4_put_super() does.

This addresses the syzbot report
"memory leak in kobject_set_name_vargs (3)"
(https://syzkaller.appspot.com/bug?extid=9f864abad79fae7c17e1).

Reported-by: syzbot+9f864abad79fae7c17e1@syzkaller.appspotmail.com
Fixes: 72ba74508b28 ("ext4: release sysfs kobject when failing to enable quotas on mount")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20200922162456.93657-1-ebiggers@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ea425b49b34567c9b20841297a6fb011c627cb6b..41953b86ffe32c1abdab4b458c73d95f1976367c 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4872,6 +4872,7 @@ cantfind_ext4:
 
 failed_mount8:
        ext4_unregister_sysfs(sb);
+       kobject_put(&sbi->s_kobj);
 failed_mount7:
        ext4_unregister_li_request(sb);
 failed_mount6: