From 04663e84f0429d3777ccb2c3f895fc8a37bddf31 Mon Sep 17 00:00:00 2001 From: Ross Lagerwall Date: Thu, 17 Jan 2019 15:34:38 +0000 Subject: net: Fix usage of pskb_trim_rcsum [ Upstream commit 6c57f0458022298e4da1729c67bd33ce41c14e7a ] In certain cases, pskb_trim_rcsum() may change skb pointers. Reinitialize header pointers afterwards to avoid potential use-after-frees. Add a note in the documentation of pskb_trim_rcsum(). Found by KASAN. Signed-off-by: Ross Lagerwall Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index e90fe6b83e00..ed329a39d621 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2962,6 +2962,7 @@ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len); * * This is exactly the same as pskb_trim except that it ensures the * checksum of received packets are still valid after the operation. + * It can change skb pointers. */ static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len) -- cgit v1.2.3 From 84d8c3a7e1a48df8d21d100181b1d97a3adc50e5 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Thu, 14 Feb 2019 11:31:17 +0100 Subject: net: create skb_gso_validate_mac_len() commit 2b16f048729bf35e6c28a40cbfad07239f9dcd90 upstream If you take a GSO skb, and split it into packets, will the MAC length (L2 + L3 + L4 headers + payload) of those packets be small enough to fit within a given length? Move skb_gso_mac_seglen() to skbuff.h with other related functions like skb_gso_network_seglen() so we can use it, and then create skb_gso_validate_mac_len to do the full calculation. Signed-off-by: Daniel Axtens Signed-off-by: David S. Miller [jwang: cherry pick for CVE-2018-1000026] Signed-off-by: Jack Wang Signed-off-by: Sasha Levin --- include/linux/skbuff.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ed329a39d621..f8761774a94f 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3102,6 +3102,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen); void skb_scrub_packet(struct sk_buff *skb, bool xnet); unsigned int skb_gso_transport_seglen(const struct sk_buff *skb); bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu); +bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len); struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features); struct sk_buff *skb_vlan_untag(struct sk_buff *skb); int skb_ensure_writable(struct sk_buff *skb, int write_len); @@ -3880,6 +3881,21 @@ static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb) return hdr_len + skb_gso_transport_seglen(skb); } +/** + * skb_gso_mac_seglen - Return length of individual segments of a gso packet + * + * @skb: GSO skb + * + * skb_gso_mac_seglen is used to determine the real size of the + * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4 + * headers (TCP/UDP). + */ +static inline unsigned int skb_gso_mac_seglen(const struct sk_buff *skb) +{ + unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb); + return hdr_len + skb_gso_transport_seglen(skb); +} + /* Local Checksum Offload. * Compute outer checksum based on the assumption that the * inner checksum will be offloaded later. -- cgit v1.2.3