Commit 96b9bd8c authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

ipv4: Fix data-races around sysctl_fib_notify_on_flag_change. 



While reading sysctl_fib_notify_on_flag_change, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its readers.

Fixes: 680aea08 ("net: ipv4: Emit notification when fib hardware flags are changed")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 870e3a63

net/ipv4/fib_trie.c

+5 −2
Original line number Diff line number Diff line
@@ -1042,6 +1042,7 @@ fib_find_matching_alias(struct net *net, const struct fib_rt_info *fri) 


void fib_alias_hw_flags_set(struct net *net, const struct fib_rt_info *fri)

{

	u8 fib_notify_on_flag_change;

	struct fib_alias *fa_match;

	struct sk_buff *skb;

	int err;
@@ -1063,14 +1064,16 @@ void fib_alias_hw_flags_set(struct net *net, const struct fib_rt_info *fri) 
	WRITE_ONCE(fa_match->offload, fri->offload);

	WRITE_ONCE(fa_match->trap, fri->trap);



	fib_notify_on_flag_change = READ_ONCE(net->ipv4.sysctl_fib_notify_on_flag_change);



	/* 2 means send notifications only if offload_failed was changed. */

	if (net->ipv4.sysctl_fib_notify_on_flag_change == 2 &&

	if (fib_notify_on_flag_change == 2 &&

	    READ_ONCE(fa_match->offload_failed) == fri->offload_failed)

		goto out;



	WRITE_ONCE(fa_match->offload_failed, fri->offload_failed);



	if (!net->ipv4.sysctl_fib_notify_on_flag_change)

	if (!fib_notify_on_flag_change)

		goto out;



	skb = nlmsg_new(fib_nlmsg_size(fa_match->fa_info), GFP_ATOMIC);