From f6c8dfa5e232c0b838a7beee27f0b7993b53a387 Mon Sep 17 00:00:00 2001 From: Haishuang Yan Date: Thu, 14 Feb 2019 13:34:43 +0800 Subject: [PATCH] ip_gre: fix parsing gre header in ipgre_err mainline inclusion from mainline-4.20 commit b0350d51f001 category: bugfix bugzilla: 5966 CVE: NA ------------------------------------------------- gre_parse_header stops parsing when csum_err is encountered, which means tpi->key is undefined and ip_tunnel_lookup will return NULL improperly. This patch introduce a NULL pointer as csum_err parameter. Even when csum_err is encountered, it won't return error and continue parsing gre header as expected. Fixes: 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook.") Reported-by: Jiri Benc Signed-off-by: Haishuang Yan Signed-off-by: David S. Miller Signed-off-by: Mao Wenan Reviewed-by: Wei Yongjun Signed-off-by: Yang Yingliang --- net/ipv4/gre_demux.c | 7 ++++--- net/ipv4/ip_gre.c | 9 +++------ 2 files changed, 7 insertions(+), 9 deletions(-) diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c index f21ea6125fc2..511b32ea2533 100644 --- a/net/ipv4/gre_demux.c +++ b/net/ipv4/gre_demux.c @@ -87,13 +87,14 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, options = (__be32 *)(greh + 1); if (greh->flags & GRE_CSUM) { - if (skb_checksum_simple_validate(skb)) { + if (!skb_checksum_simple_validate(skb)) { + skb_checksum_try_convert(skb, IPPROTO_GRE, 0, + null_compute_pseudo); + } else if (csum_err) { *csum_err = true; return -EINVAL; } - skb_checksum_try_convert(skb, IPPROTO_GRE, 0, - null_compute_pseudo); options++; } diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index f199945f6e4a..f3282ea8a80a 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -232,13 +232,10 @@ static void gre_err(struct sk_buff *skb, u32 info) const int type = icmp_hdr(skb)->type; const int code = icmp_hdr(skb)->code; struct tnl_ptk_info tpi; - bool csum_err = false; - if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), - iph->ihl * 4) < 0) { - if (!csum_err) /* ignore csum errors. */ - return; - } + if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP), + iph->ihl * 4) < 0) + return; if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { ipv4_update_pmtu(skb, dev_net(skb->dev), info, -- GitLab