Re: [PATCH] net: sock: validate data_len before allocating skb insock_alloc_send_pskb()

[Jason Wang]

On 05/30/2012 03:02 PM, David Miller wrote:
> From: Eric Dumazet<eric.dumazet@xxxxxxxxx>
> Date: Wed, 30 May 2012 08:46:23 +0200
>
> > Why doing this test in the while (1) block, it should be done before the
> > loop...
> >
> > Or even in the caller, note net/unix/af_unix.c does this right.
> >
> >          if (len>  SKB_MAX_ALLOC)
> >                  data_len = min_t(size_t,
> >                                   len - SKB_MAX_ALLOC,
> >                                   MAX_SKB_FRAGS * PAGE_SIZE);
> >
> >          skb = sock_alloc_send_pskb(sk, len - data_len, data_len,
> >                                     msg->msg_flags&  MSG_DONTWAIT,&err);
> My impression is that the callers should be fixed to.  It makes no sense
> to penalize the call sites that get this right.
>
> And yes, if we do check it in sock_alloc_send_pskb() it should be done
> at function entry, not inside the loop.

Sure, so is it ok for me to send a V2 that just do the fixing in 
sock_alloc_sned_pskb() as it's simple and easy to be accepted by stable 
version?

For the fix of callers, I want to post fixes on top as I find there's 
some code duplication of {tun|macvtap|packet}_alloc_skb() and I want to 
unify them to a common helper in sock.c. Then I can fix this issue in 
the new helper.
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