Re: [PATCH V6] netfilter: h323: avoid potential attack
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2016-02-15 20:00:00
Also in:
lkml, netfilter-devel
On Tue, Feb 02, 2016 at 09:40:04PM +0800, Zhouyi Zhou wrote:
quoted hunk ↗ jump to hunk
diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c index 9511af0..8d24c4b 100644 --- a/net/netfilter/nf_conntrack_h323_main.c +++ b/net/netfilter/nf_conntrack_h323_main.c@@ -110,6 +110,21 @@ int (*nat_q931_hook) (struct sk_buff *skb, static DEFINE_SPINLOCK(nf_h323_lock); static char *h323_buffer; +static int h323_buffer_valid_bytes; + +static bool h323_buffer_ref_valid(void *p, int len)
I'd rather see you pass a parameter to this function with the
remaining size in the buffer, so we don't need this global variable
h323_buffer_valid_bytes.
You can probably add an initial patch to add a structure to store the
state information so we reduce the function parameter footprint.
struct h323_ct_state {
...
int buflen;
};
So you pass up the h323_ct_state structure to function calls,
something like that.
Thanks.
+{
+ if ((unsigned long)len > h323_buffer_valid_bytes)
+ return false;
+
+ if (p + len > (void *)h323_buffer + h323_buffer_valid_bytes)
+ return false;
+
+ if (p < (void *)h323_buffer)
+ return false;
+
+ return true;
+}
static struct nf_conntrack_helper nf_conntrack_helper_h245;
static struct nf_conntrack_helper nf_conntrack_helper_q931[];