Commit b22f5126 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Pablo Neira Ayuso

netfilter: nf_conntrack_dccp: fix skb_header_pointer API usages

Some occurences in the netfilter tree use skb_header_pointer() in
the following way ...

  struct dccp_hdr _dh, *dh;
  ...
  skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);

... where dh itself is a pointer that is being passed as the copy
buffer. Instead, we need to use &_dh as the forth argument so that
we're copying the data into an actual buffer that sits on the stack.

Currently, we probably could overwrite memory on the stack (e.g.
with a possibly mal-formed DCCP packet), but unintentionally, as
we only want the buffer to be placed into _dh variable.

Fixes: 2bc78049 ("[NETFILTER]: nf_conntrack: add DCCP protocol support")
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 138aef7d
...@@ -428,7 +428,7 @@ static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb, ...@@ -428,7 +428,7 @@ static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
const char *msg; const char *msg;
u_int8_t state; u_int8_t state;
dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh); dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
BUG_ON(dh == NULL); BUG_ON(dh == NULL);
state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE]; state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
...@@ -486,7 +486,7 @@ static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb, ...@@ -486,7 +486,7 @@ static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
u_int8_t type, old_state, new_state; u_int8_t type, old_state, new_state;
enum ct_dccp_roles role; enum ct_dccp_roles role;
dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh); dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
BUG_ON(dh == NULL); BUG_ON(dh == NULL);
type = dh->dccph_type; type = dh->dccph_type;
...@@ -577,7 +577,7 @@ static int dccp_error(struct net *net, struct nf_conn *tmpl, ...@@ -577,7 +577,7 @@ static int dccp_error(struct net *net, struct nf_conn *tmpl,
unsigned int cscov; unsigned int cscov;
const char *msg; const char *msg;
dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh); dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
if (dh == NULL) { if (dh == NULL) {
msg = "nf_ct_dccp: short packet "; msg = "nf_ct_dccp: short packet ";
goto out_invalid; goto out_invalid;
......
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