diff options
| author | Mateusz Jurczyk <mjurczyk@google.com> | 2017-06-07 16:14:29 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-08 10:51:22 -0400 |
| commit | dd0da17b209ed91f39872766634ca967c170ada1 (patch) | |
| tree | 1d31dd81171bc855f26ac2cfb6f801b7f9889f3c | |
| parent | c164772dd32343ee19e276ce0137830557517834 (diff) | |
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 <mjurczyk@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/decnet/netfilter/dn_rtmsg.c | 4 |
1 files changed, 3 insertions, 1 deletions
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)) |