• Takashi Iwai's avatar
    ALSA: info: Fix racy addition/deletion of nodes · 8c2f8708
    Takashi Iwai authored
    The ALSA proc helper manages the child nodes in a linked list, but its
    addition and deletion is done without any lock.  This leads to a
    corruption if they are operated concurrently.  Usually this isn't a
    problem because the proc entries are added sequentially in the driver
    probe procedure itself.  But the card registrations are done often
    asynchronously, and the crash could be actually reproduced with
    syzkaller.
    
    This patch papers over it by protecting the link addition and deletion
    with the parent's mutex.  There is "access" mutex that is used for the
    file access, and this can be reused for this purpose as well.
    
    Reported-by: syzbot+48df349490c36f9f54ab@syzkaller.appspotmail.com
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    8c2f8708
info.c 20.9 KB