From 85eac2ba35a2dbfbdd5767c7447a4af07444a5b4 Mon Sep 17 00:00:00 2001 From: Mateusz Jurczyk Date: Wed, 7 Jun 2017 15:14:29 +0200 Subject: decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb Verify that the length of the socket buffer is sufficient to cover the entire nlh->nlmsg_len field before accessing that field for further input sanitization. If the client only supplies 1-3 bytes of data in sk_buff, then nlh->nlmsg_len remains partially uninitialized and contains leftover memory from the corresponding kernel allocation. Operating on such data may result in indeterminate evaluation of the nlmsg_len < sizeof(*nlh) expression. The bug was discovered by a runtime instrumentation designed to detect use of uninitialized memory in the kernel. The patch prevents this and other similar tools (e.g. KMSAN) from flagging this behavior in the future. Signed-off-by: Mateusz Jurczyk Signed-off-by: David S. Miller --- net/decnet/netfilter/dn_rtmsg.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/decnet') diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c index 1ed81ac6dd1a..26e020e9d415 100644 --- a/net/decnet/netfilter/dn_rtmsg.c +++ b/net/decnet/netfilter/dn_rtmsg.c @@ -102,7 +102,9 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb) { struct nlmsghdr *nlh = nlmsg_hdr(skb); - if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) + if (skb->len < sizeof(nlh->nlmsg_len) || + nlh->nlmsg_len < sizeof(*nlh) || + skb->len < nlh->nlmsg_len) return; if (!netlink_capable(skb, CAP_NET_ADMIN)) -- cgit v1.2.3 From c164772dd32343ee19e276ce0137830557517834 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 8 Jun 2017 10:50:18 -0400 Subject: Revert "decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb" This reverts commit 85eac2ba35a2dbfbdd5767c7447a4af07444a5b4. There is an updated version of this fix which we should use instead. Signed-off-by: David S. Miller --- net/decnet/netfilter/dn_rtmsg.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'net/decnet') diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c index 26e020e9d415..1ed81ac6dd1a 100644 --- a/net/decnet/netfilter/dn_rtmsg.c +++ b/net/decnet/netfilter/dn_rtmsg.c @@ -102,9 +102,7 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb) { struct nlmsghdr *nlh = nlmsg_hdr(skb); - if (skb->len < sizeof(nlh->nlmsg_len) || - nlh->nlmsg_len < sizeof(*nlh) || - skb->len < nlh->nlmsg_len) + if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) return; if (!netlink_capable(skb, CAP_NET_ADMIN)) -- cgit v1.2.3 From dd0da17b209ed91f39872766634ca967c170ada1 Mon Sep 17 00:00:00 2001 From: Mateusz Jurczyk Date: Wed, 7 Jun 2017 16:14:29 +0200 Subject: decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb Verify that the length of the socket buffer is sufficient to cover the nlmsghdr structure before accessing the nlh->nlmsg_len field for further input sanitization. If the client only supplies 1-3 bytes of data in sk_buff, then nlh->nlmsg_len remains partially uninitialized and contains leftover memory from the corresponding kernel allocation. Operating on such data may result in indeterminate evaluation of the nlmsg_len < sizeof(*nlh) expression. The bug was discovered by a runtime instrumentation designed to detect use of uninitialized memory in the kernel. The patch prevents this and other similar tools (e.g. KMSAN) from flagging this behavior in the future. Signed-off-by: Mateusz Jurczyk Signed-off-by: David S. Miller --- net/decnet/netfilter/dn_rtmsg.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/decnet') diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c index 1ed81ac6dd1a..aa8ffecc46a4 100644 --- a/net/decnet/netfilter/dn_rtmsg.c +++ b/net/decnet/netfilter/dn_rtmsg.c @@ -102,7 +102,9 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb) { struct nlmsghdr *nlh = nlmsg_hdr(skb); - if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) + if (skb->len < sizeof(*nlh) || + nlh->nlmsg_len < sizeof(*nlh) || + skb->len < nlh->nlmsg_len) return; if (!netlink_capable(skb, CAP_NET_ADMIN)) -- cgit v1.2.3