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Commit 220815a9 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
Browse files

genetlink: fix genlmsg_multicast() bug 



Unfortunately, I introduced a tremendously stupid bug into
genlmsg_multicast() when doing all those multicast group
changes: it adjusts the group number, but then passes it
to genlmsg_multicast_netns() which does that again.

Somehow, my tests failed to catch this, so add a warning
into genlmsg_multicast_netns() and remove the offending
group ID adjustment.

Also add a warning to the similar code in other functions
so people who misuse them are more loudly warned.

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e40526cb

include/net/genetlink.h

+1 −4
Original line number Diff line number Diff line
@@ -265,7 +265,7 @@ static inline int genlmsg_multicast_netns(struct genl_family *family, 
					  struct net *net, struct sk_buff *skb,

					  u32 portid, unsigned int group, gfp_t flags)

{

	if (group >= family->n_mcgrps)

	if (WARN_ON_ONCE(group >= family->n_mcgrps))

		return -EINVAL;

	group = family->mcgrp_offset + group;

	return nlmsg_multicast(net->genl_sock, skb, portid, group, flags);
@@ -283,9 +283,6 @@ static inline int genlmsg_multicast(struct genl_family *family, 
				    struct sk_buff *skb, u32 portid,

				    unsigned int group, gfp_t flags)

{

	if (group >= family->n_mcgrps)

		return -EINVAL;

	group = family->mcgrp_offset + group;

	return genlmsg_multicast_netns(family, &init_net, skb,

				       portid, group, flags);

}

net/netlink/genetlink.c

+2 −2
Original line number Diff line number Diff line
@@ -1045,7 +1045,7 @@ static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, 
int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,

			    u32 portid, unsigned int group, gfp_t flags)

{

	if (group >= family->n_mcgrps)

	if (WARN_ON_ONCE(group >= family->n_mcgrps))

		return -EINVAL;

	group = family->mcgrp_offset + group;

	return genlmsg_mcast(skb, portid, group, flags);
@@ -1062,7 +1062,7 @@ void genl_notify(struct genl_family *family, 
	if (nlh)

		report = nlmsg_report(nlh);



	if (group >= family->n_mcgrps)

	if (WARN_ON_ONCE(group >= family->n_mcgrps))

		return;

	group = family->mcgrp_offset + group;

	nlmsg_notify(sk, skb, portid, group, report, flags);