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Date: Fri, 12 Apr 2013 11:07:47 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Grégoire Baron <baronchon@...m.org>
Subject: [PATCH net-next] act_csum: fix possible use after free
From: Eric Dumazet <edumazet@...gle.com>
tcf_csum_skb_nextlayer() / pskb_may_pull() can change skb->head, so we
must be careful not keeping pointers to previous headers.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Grégoire Baron <baronchon@...m.org>
---
Compile tested only, a probation period on net-next is welcomed
net/sched/act_csum.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index 08fa1e8..3a4c0ca 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -166,15 +166,17 @@ static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
return 1;
}
-static int tcf_csum_ipv6_icmp(struct sk_buff *skb, struct ipv6hdr *ip6h,
+static int tcf_csum_ipv6_icmp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl)
{
struct icmp6hdr *icmp6h;
+ const struct ipv6hdr *ip6h;
icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
if (icmp6h == NULL)
return 0;
+ ip6h = ipv6_hdr(skb);
icmp6h->icmp6_cksum = 0;
skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
@@ -186,15 +188,17 @@ static int tcf_csum_ipv6_icmp(struct sk_buff *skb, struct ipv6hdr *ip6h,
return 1;
}
-static int tcf_csum_ipv4_tcp(struct sk_buff *skb, struct iphdr *iph,
+static int tcf_csum_ipv4_tcp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl)
{
struct tcphdr *tcph;
+ const struct iphdr *iph;
tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
if (tcph == NULL)
return 0;
+ iph = ip_hdr(skb);
tcph->check = 0;
skb->csum = csum_partial(tcph, ipl - ihl, 0);
tcph->check = tcp_v4_check(ipl - ihl,
@@ -205,15 +209,17 @@ static int tcf_csum_ipv4_tcp(struct sk_buff *skb, struct iphdr *iph,
return 1;
}
-static int tcf_csum_ipv6_tcp(struct sk_buff *skb, struct ipv6hdr *ip6h,
+static int tcf_csum_ipv6_tcp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl)
{
struct tcphdr *tcph;
+ const struct ipv6hdr *ip6h;
tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
if (tcph == NULL)
return 0;
+ ip6h = ipv6_hdr(skb);
tcph->check = 0;
skb->csum = csum_partial(tcph, ipl - ihl, 0);
tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
@@ -225,10 +231,11 @@ static int tcf_csum_ipv6_tcp(struct sk_buff *skb, struct ipv6hdr *ip6h,
return 1;
}
-static int tcf_csum_ipv4_udp(struct sk_buff *skb, struct iphdr *iph,
+static int tcf_csum_ipv4_udp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl, int udplite)
{
struct udphdr *udph;
+ const struct iphdr *iph;
u16 ul;
/*
@@ -242,6 +249,7 @@ static int tcf_csum_ipv4_udp(struct sk_buff *skb, struct iphdr *iph,
if (udph == NULL)
return 0;
+ iph = ip_hdr(skb);
ul = ntohs(udph->len);
if (udplite || udph->check) {
@@ -276,10 +284,11 @@ ignore_obscure_skb:
return 1;
}
-static int tcf_csum_ipv6_udp(struct sk_buff *skb, struct ipv6hdr *ip6h,
+static int tcf_csum_ipv6_udp(struct sk_buff *skb,
unsigned int ihl, unsigned int ipl, int udplite)
{
struct udphdr *udph;
+ const struct ipv6hdr *ip6h;
u16 ul;
/*
@@ -293,6 +302,7 @@ static int tcf_csum_ipv6_udp(struct sk_buff *skb, struct ipv6hdr *ip6h,
if (udph == NULL)
return 0;
+ ip6h = ipv6_hdr(skb);
ul = ntohs(udph->len);
udph->check = 0;
@@ -328,7 +338,7 @@ ignore_obscure_skb:
static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
{
- struct iphdr *iph;
+ const struct iphdr *iph;
int ntkoff;
ntkoff = skb_network_offset(skb);
@@ -353,19 +363,19 @@ static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
break;
case IPPROTO_TCP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
- if (!tcf_csum_ipv4_tcp(skb, iph, iph->ihl * 4,
+ if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4,
ntohs(iph->tot_len)))
goto fail;
break;
case IPPROTO_UDP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
- if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4,
+ if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
ntohs(iph->tot_len), 0))
goto fail;
break;
case IPPROTO_UDPLITE:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
- if (!tcf_csum_ipv4_udp(skb, iph, iph->ihl * 4,
+ if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
ntohs(iph->tot_len), 1))
goto fail;
break;
@@ -377,7 +387,7 @@ static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
goto fail;
- ip_send_check(iph);
+ ip_send_check(ip_hdr(skb));
}
return 1;
@@ -456,6 +466,7 @@ static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
ixhl = ipv6_optlen(ip6xh);
if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
goto fail;
+ ip6xh = (void *)(skb_network_header(skb) + hl);
if ((nexthdr == NEXTHDR_HOP) &&
!(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
goto fail;
@@ -464,25 +475,25 @@ static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
break;
case IPPROTO_ICMPV6:
if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
- if (!tcf_csum_ipv6_icmp(skb, ip6h,
+ if (!tcf_csum_ipv6_icmp(skb,
hl, pl + sizeof(*ip6h)))
goto fail;
goto done;
case IPPROTO_TCP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
- if (!tcf_csum_ipv6_tcp(skb, ip6h,
+ if (!tcf_csum_ipv6_tcp(skb,
hl, pl + sizeof(*ip6h)))
goto fail;
goto done;
case IPPROTO_UDP:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
- if (!tcf_csum_ipv6_udp(skb, ip6h, hl,
+ if (!tcf_csum_ipv6_udp(skb, hl,
pl + sizeof(*ip6h), 0))
goto fail;
goto done;
case IPPROTO_UDPLITE:
if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
- if (!tcf_csum_ipv6_udp(skb, ip6h, hl,
+ if (!tcf_csum_ipv6_udp(skb, hl,
pl + sizeof(*ip6h), 1))
goto fail;
goto done;
--
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