[ Upstream commit 8dfb4eba4100e7cdd161a8baef2d8d61b7a7e62e ]
esp_output_udp_encap can produce a length that doesn't fit in the 16 bits of a UDP header's length field. In that case, we'll send a fragmented packet whose length is larger than IP_MAX_MTU (resulting in "Oversized IP packet" warnings on receive) and with a bogus UDP length.
To prevent this, add a length check to esp_output_udp_encap and return -EMSGSIZE on failure.
This seems to be older than git history.
Signed-off-by: Sabrina Dubroca sd@queasysnail.net Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/esp4.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index d30285c5d52dd..c8e32f167ebbf 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -205,7 +205,7 @@ static void esp_output_fill_trailer(u8 *tail, int tfclen, int plen, __u8 proto) tail[plen - 1] = proto; }
-static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) +static int esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) { int encap_type; struct udphdr *uh; @@ -213,6 +213,7 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru __be16 sport, dport; struct xfrm_encap_tmpl *encap = x->encap; struct ip_esp_hdr *esph = esp->esph; + unsigned int len;
spin_lock_bh(&x->lock); sport = encap->encap_sport; @@ -220,11 +221,14 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru encap_type = encap->encap_type; spin_unlock_bh(&x->lock);
+ len = skb->len + esp->tailen - skb_transport_offset(skb); + if (len + sizeof(struct iphdr) >= IP_MAX_MTU) + return -EMSGSIZE; + uh = (struct udphdr *)esph; uh->source = sport; uh->dest = dport; - uh->len = htons(skb->len + esp->tailen - - skb_transport_offset(skb)); + uh->len = htons(len); uh->check = 0;
switch (encap_type) { @@ -241,6 +245,8 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru
*skb_mac_header(skb) = IPPROTO_UDP; esp->esph = esph; + + return 0; }
int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) @@ -254,8 +260,12 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * int tailen = esp->tailen;
/* this is non-NULL only with UDP Encapsulation */ - if (x->encap) - esp_output_udp_encap(x, skb, esp); + if (x->encap) { + int err = esp_output_udp_encap(x, skb, esp); + + if (err < 0) + return err; + }
if (!skb_cloned(skb)) { if (tailen <= skb_tailroom(skb)) {