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authorDavid Gibson <david@gibson.dropbear.id.au>2014-04-24 10:22:35 +1000
committerDavid S. Miller <davem@davemloft.net>2014-04-24 13:52:54 -0400
commit973462bbde79bb827824c73b59027a0aed5c9ca6 (patch)
treefdf9ac5d381071d750adb9cb81e406a2b16fd58f /net
parenta64d90fd962c2956da7505f98a302408450365e2 (diff)
rtnetlink: Warn when interface's information won't fit in our packet
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>
Diffstat (limited to 'net')
-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 64ad17d077e..8db72ac88fe 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1198,6 +1198,7 @@ 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];
@@ -1218,11 +1219,17 @@ 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));