This is a note to let you know that I've just added the patch titled netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv to the 4.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: netfilter-nfnetlink-improve-input-length-sanitization-in-nfnetlink_rcv.patch and it can be found in the queue-4.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f55ce7b024090a51382ccab2730b96e2f7b4e9cf Mon Sep 17 00:00:00 2001 From: Mateusz Jurczyk <mjurczyk@xxxxxxxxxx> Date: Wed, 7 Jun 2017 15:50:38 +0200 Subject: netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv From: Mateusz Jurczyk <mjurczyk@xxxxxxxxxx> commit f55ce7b024090a51382ccab2730b96e2f7b4e9cf upstream. 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 < NLMSG_HDRLEN 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 <mjurczyk@xxxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Cc: Florian Westphal <fw@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/netfilter/nfnetlink.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -463,8 +463,7 @@ static void nfnetlink_rcv_skb_batch(stru if (msglen > skb->len) msglen = skb->len; - if (nlh->nlmsg_len < NLMSG_HDRLEN || - skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) + if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) return; err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy, @@ -491,7 +490,8 @@ static void nfnetlink_rcv(struct sk_buff { struct nlmsghdr *nlh = nlmsg_hdr(skb); - if (nlh->nlmsg_len < NLMSG_HDRLEN || + if (skb->len < NLMSG_HDRLEN || + nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) return; Patches currently in stable-queue which might be from mjurczyk@xxxxxxxxxx are queue-4.12/netfilter-nfnetlink-improve-input-length-sanitization-in-nfnetlink_rcv.patch