[PATCH] ipv6: ip6t_srh: fix NULL pointer dereferences

Kangjie Lu
2019-03-14T07:58:32Z

skb_header_pointer may return NULL. The current code dereference
its return values without a NULL check.

The fix inserts the checks to avoid NULL pointer dereferences.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
net/ipv6/netfilter/ip6t_srh.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/ipv6/netfilter/ip6t_srh.c b/net/ipv6/netfilter/ip6t_srh.c
index 1059894a6f4c..4cb83fb69844 100644
--- a/net/ipv6/netfilter/ip6t_srh.c
+++ b/net/ipv6/netfilter/ip6t_srh.c
@@ -210,6 +210,8 @@ static bool srh1_mt6(const struct sk_buff *skb, struct xt_action_param *par)
psidoff = srhoff + sizeof(struct ipv6_sr_hdr) +
((srh->segments_left + 1) * sizeof(struct in6_addr));
psid = skb_header_pointer(skb, psidoff, sizeof(_psid), &_psid);
+ if (!psid)
+ return false;
if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_PSID,
ipv6_masked_addr_cmp(psid, &srhinfo->psid_msk,
&srhinfo->psid_addr)))
@@ -223,6 +225,8 @@ static bool srh1_mt6(const struct sk_buff *skb, struct xt_action_param *par)
nsidoff = srhoff + sizeof(struct ipv6_sr_hdr) +
((srh->segments_left - 1) * sizeof(struct in6_addr));
nsid = skb_header_pointer(skb, nsidoff, sizeof(_nsid), &_nsid);
+ if (!nsid)
+ return false;
if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_NSID,
ipv6_masked_addr_cmp(nsid, &srhinfo->nsid_msk,
&srhinfo->nsid_addr)))
@@ -233,6 +237,8 @@ static bool srh1_mt6(const struct sk_buff *skb, struct xt_action_param *par)
if (srhinfo->mt_flags & IP6T_SRH_LSID) {
lsidoff = srhoff + sizeof(struct ipv6_sr_hdr);
lsid = skb_header_pointer(skb, lsidoff, sizeof(_lsid), &_lsid);
+ if (!lsid)
+ return false;
if (NF_SRH_INVF(srhinfo, IP6T_SRH_INV_LSID,
ipv6_masked_addr_cmp(lsid, &srhinfo->lsid_msk,
&srhinfo->lsid_addr)))
--
2.17.1