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

Chen Gang
2012-11-26T01:33:46Z

于 2012年11月26日 09:22, Chen Gang 写道:
> 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 "pimre%u" (or another format), will not hurt the functional features, I suggest to use it
since, we need try our best to not touch the OS API.
("pimreg%u" seems an internal format, not OS API Level)

>
> 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