• David S. Miller's avatar
    net: Fix use after free by removing length arg from sk_data_ready callbacks. · 676d2369
    David S. Miller authored
    Several spots in the kernel perform a sequence like:
    
    	skb_queue_tail(&sk->s_receive_queue, skb);
    	sk->sk_data_ready(sk, skb->len);
    
    But at the moment we place the SKB onto the socket receive queue it
    can be consumed and freed up.  So this skb->len access is potentially
    to freed up memory.
    
    Furthermore, the skb->len can be modified by the consumer so it is
    possible that the value isn't accurate.
    
    And finally, no actual implementation of this callback actually uses
    the length argument.  And since nobody actually cared about it's
    value, lots of call sites pass arbitrary values in such as '0' and
    even '1'.
    
    So just remove the length argument from the callback, that way there
    is no confusion whatsoever and all of these use-after-free cases get
    fixed as a side effect.
    
    Based upon a patch by Eric Dumazet and his suggestion to audit this
    issue tree-wide.
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    676d2369
mpc.c 38.2 KB