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

Chen Gang
2012-11-26T01:22:01Z

于 2012年11月26日 03:44, Eric Dumazet 写道:
> From: Eric Dumazet <edumazet@google.com>
>
> 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 <gang.chen@asianux.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
> 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