diff options
| author | Mateusz Jurczyk <mjurczyk@google.com> | 2017-06-07 15:14:29 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-08 10:38:54 -0400 |
| commit | 85eac2ba35a2dbfbdd5767c7447a4af07444a5b4 (patch) | |
| tree | be809e06a3e4330b99b82ed588b359f8e013cf87 | |
| parent | ed66e50d9587fc0bb032e276a2563c0068a5b63a (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
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 <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..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)) |