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authorDavid S. Miller <davem@davemloft.net>2018-12-07 16:24:40 -0800
committerDavid S. Miller <davem@davemloft.net>2018-12-07 16:24:40 -0800
commit8b78903bc5f1786f7f988d26de48819144a13d6c (patch)
tree9b93e099315cb036f69df1d45cac0e98de166976
parentf9bfe4e6a9d08d405fe7b081ee9a13e649c97ecf (diff)
parente6ac64d4c4d095085d7dd71cbd05704ac99829b2 (diff)
downloadlinux-stericsson-8b78903bc5f1786f7f988d26de48819144a13d6c.tar.gz
Merge branch 'skb-headroom-slab-out-of-bounds'
Stefano Brivio says: ==================== Fix slab out-of-bounds on insufficient headroom for IPv6 packets Patch 1/2 fixes a slab out-of-bounds occurring with short SCTP packets over IPv4 over L2TP over IPv6 on a configuration with relatively low HEADER_MAX. Patch 2/2 makes sure we avoid writing before the allocated buffer in neigh_hh_output() in case the headroom is enough for the unaligned hardware header size, but not enough for the aligned one, and that we warn if we hit this condition. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/neighbour.h28
-rw-r--r--net/ipv6/ip6_output.c42
2 files changed, 44 insertions, 26 deletions
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index f58b384aa6c9..665990c7dec8 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -454,6 +454,7 @@ static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
{
+ unsigned int hh_alen = 0;
unsigned int seq;
unsigned int hh_len;
@@ -461,16 +462,33 @@ static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb
seq = read_seqbegin(&hh->hh_lock);
hh_len = hh->hh_len;
if (likely(hh_len <= HH_DATA_MOD)) {
- /* this is inlined by gcc */
- memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
+ hh_alen = HH_DATA_MOD;
+
+ /* skb_push() would proceed silently if we have room for
+ * the unaligned size but not for the aligned size:
+ * check headroom explicitly.
+ */
+ if (likely(skb_headroom(skb) >= HH_DATA_MOD)) {
+ /* this is inlined by gcc */
+ memcpy(skb->data - HH_DATA_MOD, hh->hh_data,
+ HH_DATA_MOD);
+ }
} else {
- unsigned int hh_alen = HH_DATA_ALIGN(hh_len);
+ hh_alen = HH_DATA_ALIGN(hh_len);
- memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
+ if (likely(skb_headroom(skb) >= hh_alen)) {
+ memcpy(skb->data - hh_alen, hh->hh_data,
+ hh_alen);
+ }
}
} while (read_seqretry(&hh->hh_lock, seq));
- skb_push(skb, hh_len);
+ if (WARN_ON_ONCE(skb_headroom(skb) < hh_alen)) {
+ kfree_skb(skb);
+ return NET_XMIT_DROP;
+ }
+
+ __skb_push(skb, hh_len);
return dev_queue_xmit(skb);
}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 827a3f5ff3bb..fcd3c66ded16 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -195,37 +195,37 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
const struct ipv6_pinfo *np = inet6_sk(sk);
struct in6_addr *first_hop = &fl6->daddr;
struct dst_entry *dst = skb_dst(skb);
+ unsigned int head_room;
struct ipv6hdr *hdr;
u8 proto = fl6->flowi6_proto;
int seg_len = skb->len;
int hlimit = -1;
u32 mtu;
- if (opt) {
- unsigned int head_room;
+ head_room = sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
+ if (opt)
+ head_room += opt->opt_nflen + opt->opt_flen;
- /* First: exthdrs may take lots of space (~8K for now)
- MAX_HEADER is not enough.
- */
- head_room = opt->opt_nflen + opt->opt_flen;
- seg_len += head_room;
- head_room += sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
-
- if (skb_headroom(skb) < head_room) {
- struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
- if (!skb2) {
- IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
- IPSTATS_MIB_OUTDISCARDS);
- kfree_skb(skb);
- return -ENOBUFS;
- }
- if (skb->sk)
- skb_set_owner_w(skb2, skb->sk);
- consume_skb(skb);
- skb = skb2;
+ if (unlikely(skb_headroom(skb) < head_room)) {
+ struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
+ if (!skb2) {
+ IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+ IPSTATS_MIB_OUTDISCARDS);
+ kfree_skb(skb);
+ return -ENOBUFS;
}
+ if (skb->sk)
+ skb_set_owner_w(skb2, skb->sk);
+ consume_skb(skb);
+ skb = skb2;
+ }
+
+ if (opt) {
+ seg_len += opt->opt_nflen + opt->opt_flen;
+
if (opt->opt_flen)
ipv6_push_frag_opts(skb, opt, &proto);
+
if (opt->opt_nflen)
ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop,
&fl6->saddr);