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authorKees Cook <keescook@chromium.org>2022-09-02 21:37:49 -0700
committerDavid S. Miller <davem@davemloft.net>2022-09-05 14:45:22 +0100
commit710d21fdff9a98d621cd4e64167f3ef8af4e2fd1 (patch)
treec039cd1cbfc4dc5dc57138e1d5752e155810be5a /net/netlink
parent05ad5d4581c3c1cc724fe50d4652833fb9f3037b (diff)
downloadlwn-710d21fdff9a98d621cd4e64167f3ef8af4e2fd1.tar.gz
lwn-710d21fdff9a98d621cd4e64167f3ef8af4e2fd1.zip
netlink: Bounds-check struct nlmsgerr creation
In preparation for FORTIFY_SOURCE doing bounds-check on memcpy(), switch from __nlmsg_put to nlmsg_put(), and explain the bounds check for dealing with the memcpy() across a composite flexible array struct. Avoids this future run-time warning: memcpy: detected field-spanning write (size 32) of single field "&errmsg->msg" at net/netlink/af_netlink.c:2447 (size 16) Cc: Jakub Kicinski <kuba@kernel.org> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Jozsef Kadlecsik <kadlec@netfilter.org> Cc: Florian Westphal <fw@strlen.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: syzbot <syzkaller@googlegroups.com> Cc: netfilter-devel@vger.kernel.org Cc: coreteam@netfilter.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220901071336.1418572-1-keescook@chromium.org Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
-rw-r--r--net/netlink/af_netlink.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index f89ba302ac6e..a662e8a5ff84 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2494,11 +2494,13 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
return;
}
- rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
- NLMSG_ERROR, payload, flags);
+ rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+ NLMSG_ERROR, payload, flags);
errmsg = nlmsg_data(rep);
errmsg->error = err;
- memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+ unsafe_memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg)
+ ? nlh->nlmsg_len : sizeof(*nlh),
+ /* Bounds checked by the skb layer. */);
if (tlvlen)
netlink_ack_tlv_fill(in_skb, skb, nlh, err, extack);