| Message ID | 1454037935-14842-1-git-send-email-zhouzhouyi@gmail.com |
|---|---|
| State | Changes Requested |
| Delegated to: | Pablo Neira |
| Headers | show |
On Fri, Jan 29, 2016 at 11:25:35AM +0800, Zhouyi Zhou wrote: > I think hackers chould build a malicious h323 packet to overflow > the pointer p which will panic during the memcpy(addr, p, len) > For example, he may fabricate a very large taddr->ipAddress.ip; > As suggested by Eric, this module is protected by a lock (nf_h323_lock) > so adding a variable h323_buffer_valid_bytes that would contain > the number of valid bytes would not require to change prototypes of > get_h2x5_addr. > > Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > > --- > net/netfilter/nf_conntrack_h323_main.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c > index 9511af0..65d84bc 100644 > --- a/net/netfilter/nf_conntrack_h323_main.c > +++ b/net/netfilter/nf_conntrack_h323_main.c > @@ -110,6 +110,11 @@ int (*nat_q931_hook) (struct sk_buff *skb, > > static DEFINE_SPINLOCK(nf_h323_lock); > static char *h323_buffer; > +static unsigned int h323_buffer_valid_bytes; > +/* check offset overflow and out of range data reference */ > +#define CHECK_BOUND(p, n) ((n) > h323_buffer_valid_bytes || \ > + ((void *)(p) + (n) - (void *)h323_buffer \ > + > h323_buffer_valid_bytes)) We don't want obscure macros. You add a function for this, the compiler will likely inline it. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2016-02-01 at 18:58 +0100, Pablo Neira Ayuso wrote: > On Fri, Jan 29, 2016 at 11:25:35AM +0800, Zhouyi Zhou wrote: > > I think hackers chould build a malicious h323 packet to overflow > > the pointer p which will panic during the memcpy(addr, p, len) > > For example, he may fabricate a very large taddr->ipAddress.ip; > > As suggested by Eric, this module is protected by a lock (nf_h323_lock) > > so adding a variable h323_buffer_valid_bytes that would contain > > the number of valid bytes would not require to change prototypes of > > get_h2x5_addr. > > > > Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn> > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > > Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > > > > --- > > net/netfilter/nf_conntrack_h323_main.c | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c > > index 9511af0..65d84bc 100644 > > --- a/net/netfilter/nf_conntrack_h323_main.c > > +++ b/net/netfilter/nf_conntrack_h323_main.c > > @@ -110,6 +110,11 @@ int (*nat_q931_hook) (struct sk_buff *skb, > > > > static DEFINE_SPINLOCK(nf_h323_lock); > > static char *h323_buffer; > > +static unsigned int h323_buffer_valid_bytes; > > +/* check offset overflow and out of range data reference */ > > +#define CHECK_BOUND(p, n) ((n) > h323_buffer_valid_bytes || \ > > + ((void *)(p) + (n) - (void *)h323_buffer \ > > + > h323_buffer_valid_bytes)) > > We don't want obscure macros. You add a function for this, the > compiler will likely inline it. BTW, I did not signed-off this patch. Zhouyi Zho, just add your own signature, let people add their own. Thanks. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c index 9511af0..65d84bc 100644 --- a/net/netfilter/nf_conntrack_h323_main.c +++ b/net/netfilter/nf_conntrack_h323_main.c @@ -110,6 +110,11 @@ int (*nat_q931_hook) (struct sk_buff *skb, static DEFINE_SPINLOCK(nf_h323_lock); static char *h323_buffer; +static unsigned int h323_buffer_valid_bytes; +/* check offset overflow and out of range data reference */ +#define CHECK_BOUND(p, n) ((n) > h323_buffer_valid_bytes || \ + ((void *)(p) + (n) - (void *)h323_buffer \ + > h323_buffer_valid_bytes)) static struct nf_conntrack_helper nf_conntrack_helper_h245; static struct nf_conntrack_helper nf_conntrack_helper_q931[]; @@ -145,6 +150,7 @@ static int get_tpkt_data(struct sk_buff *skb, unsigned int protoff, if (*data == NULL) { /* first TPKT */ /* Get first TPKT pointer */ + h323_buffer_valid_bytes = tcpdatalen; tpkt = skb_header_pointer(skb, tcpdataoff, tcpdatalen, h323_buffer); BUG_ON(tpkt == NULL); @@ -247,6 +253,9 @@ static int get_h245_addr(struct nf_conn *ct, const unsigned char *data, return 0; } + if (CHECK_BOUND(p, len + sizeof(__be16))) + return 0; + memcpy(addr, p, len); memset((void *)addr + len, 0, sizeof(*addr) - len); memcpy(port, p + len, sizeof(__be16)); @@ -669,6 +678,9 @@ int get_h225_addr(struct nf_conn *ct, unsigned char *data, return 0; } + if (CHECK_BOUND(p, len + sizeof(__be16))) + return 0; + memcpy(addr, p, len); memset((void *)addr + len, 0, sizeof(*addr) - len); memcpy(port, p + len, sizeof(__be16)); @@ -1248,6 +1260,7 @@ static unsigned char *get_udp_data(struct sk_buff *skb, unsigned int protoff, if (dataoff >= skb->len) return NULL; *datalen = skb->len - dataoff; + h323_buffer_valid_bytes = *datalen; return skb_header_pointer(skb, dataoff, *datalen, h323_buffer); }