Subject: Re: [PATCH] net: ipmr: limit MRT_TABLE identifiers

From: Chen Gang <[email-masked]>
Date: Mon, 26 Nov 2012 09:22:56 +0800

于 2012年11月26日 03:44, Eric Dumazet 写道:
> From: Eric Dumazet <[email-masked]>
> 
> Name of pimreg devices are built from following format :
> 
> char name[IFNAMSIZ]; // IFNAMSIZ == 16
> 
> sprintf(name, "pimreg%u", mrt->id);
> 
> We must therefore limit mrt->id to 9 decimal digits
> or risk a buffer overflow and a crash.
> 
> Restrict table identifiers in [0 ... 999999999] interval.
> 

  if we have to stick to "pimreg%u" (or will hurt the functional features)
  suggest to let user mode know this limitation. 
    define a macro in public header (user mode can know it) and give comments.
    use macro instead of number.
    remove the comments which is inside internal function.

  thanks.

gchen.

> Reported-by: Chen Gang <[email-masked]>
> Signed-off-by: Eric Dumazet <[email-masked]>
> ---
>  net/ipv4/ipmr.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 6168c4d..3eab2b2 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -1318,6 +1318,10 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
>  		if (get_user(v, (u32 __user *)optval))
>  			return -EFAULT;
>  
> +		/* "pimreg%u" should not exceed 16 bytes (IFNAMSIZ) */
> +		if (v != RT_TABLE_DEFAULT && v >= 1000000000)
> +			return -EINVAL;
> +
>  		rtnl_lock();
>  		ret = 0;
>  		if (sk == rtnl_dereference(mrt->mroute_sk)) {
> 
> 
> 
> 

-- 
Chen Gang

Asianux Corporation