summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorDavid Gibson <david@gibson.dropbear.id.au>2014-04-24 10:22:35 +1000
committerJiri Slaby <jslaby@suse.cz>2014-05-29 11:49:18 +0200
commit5a6aea7c0eaa0a2a851f80aa646ebb65d76c51fe (patch)
treebf627c9acd132d09f086c3cf14aef64a942b1a1f
parent6bebcc8d95669e32c9ac6e836e985ae50392ae23 (diff)
downloadlwn-5a6aea7c0eaa0a2a851f80aa646ebb65d76c51fe.tar.gz
lwn-5a6aea7c0eaa0a2a851f80aa646ebb65d76c51fe.zip
rtnetlink: Warn when interface's information won't fit in our packet
[ Upstream commit 973462bbde79bb827824c73b59027a0aed5c9ca6 ] Without IFLA_EXT_MASK specified, the information reported for a single interface in response to RTM_GETLINK is expected to fit within a netlink packet of NLMSG_GOODSIZE. If it doesn't, however, things will go badly wrong, When listing all interfaces, netlink_dump() will incorrectly treat -EMSGSIZE on the first message in a packet as the end of the listing and omit information for that interface and all subsequent ones. This can cause getifaddrs(3) to enter an infinite loop. This patch won't fix the problem, but it will WARN_ON() making it easier to track down what's going wrong. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Jiri Pirko <jpirko@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
-rw-r--r--net/core/rtnetlink.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 37b492eaa4f8..d320d30fb6bb 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1070,6 +1070,7 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
struct hlist_head *head;
struct nlattr *tb[IFLA_MAX+1];
u32 ext_filter_mask = 0;
+ int err;
s_h = cb->args[0];
s_idx = cb->args[1];
@@ -1090,11 +1091,17 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
hlist_for_each_entry_rcu(dev, head, index_hlist) {
if (idx < s_idx)
goto cont;
- if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
- NETLINK_CB(cb->skb).portid,
- cb->nlh->nlmsg_seq, 0,
- NLM_F_MULTI,
- ext_filter_mask) <= 0)
+ err = rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
+ NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq, 0,
+ NLM_F_MULTI,
+ ext_filter_mask);
+ /* If we ran out of room on the first message,
+ * we're in trouble
+ */
+ WARN_ON((err == -EMSGSIZE) && (skb->len == 0));
+
+ if (err <= 0)
goto out;
nl_dump_check_consistent(cb, nlmsg_hdr(skb));