Linux Kernel Mentees Archive on lore.kernel.org
 help / color / Atom feed
* [Linux-kernel-mentees] [PATCH net v2] ipv6: Fix suspicious RCU usage warning in ip6mr
@ 2020-05-16  7:45 madhuparnabhowmik10
  2020-05-16 20:43 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: madhuparnabhowmik10 @ 2020-05-16  7:45 UTC (permalink / raw)
  To: davem, kuznet, yoshfuji, kuba, kaber
  Cc: paulmck, netdev, linux-kernel, Madhuparna Bhowmik, cai, joel,
	linux-kernel-mentees

From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

This patch fixes the following warning:

=============================
WARNING: suspicious RCU usage
5.7.0-rc4-next-20200507-syzkaller #0 Not tainted
-----------------------------
net/ipv6/ip6mr.c:124 RCU-list traversed in non-reader section!!

ipmr_new_table() returns an existing table, but there is no table at
init. Therefore the condition: either holding rtnl or the list is empty
is used.

Fixes: d1db275dd3f6e ("ipv6: ip6mr: support multiple tables")
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
---
v2:
- Add correct fixes tag
- Fix line over 80 chars

 net/ipv6/ip6mr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 65a54d74acc1..1e223e26f079 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -98,7 +98,8 @@ static void ipmr_expire_process(struct timer_list *t);
 #ifdef CONFIG_IPV6_MROUTE_MULTIPLE_TABLES
 #define ip6mr_for_each_table(mrt, net) \
 	list_for_each_entry_rcu(mrt, &net->ipv6.mr6_tables, list, \
-				lockdep_rtnl_is_held())
+				lockdep_rtnl_is_held() || \
+				list_empty(&net->ipv6.mr6_tables))
 
 static struct mr_table *ip6mr_mr_table_iter(struct net *net,
 					    struct mr_table *mrt)
-- 
2.17.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [Linux-kernel-mentees] [PATCH net v2] ipv6: Fix suspicious RCU usage warning in ip6mr
  2020-05-16  7:45 [Linux-kernel-mentees] [PATCH net v2] ipv6: Fix suspicious RCU usage warning in ip6mr madhuparnabhowmik10
@ 2020-05-16 20:43 ` David Miller
  0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2020-05-16 20:43 UTC (permalink / raw)
  To: madhuparnabhowmik10
  Cc: paulmck, yoshfuji, netdev, linux-kernel, cai, kuba, joel, kuznet,
	linux-kernel-mentees, kaber

From: madhuparnabhowmik10@gmail.com
Date: Sat, 16 May 2020 13:15:15 +0530

> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> 
> This patch fixes the following warning:
> 
> =============================
> WARNING: suspicious RCU usage
> 5.7.0-rc4-next-20200507-syzkaller #0 Not tainted
> -----------------------------
> net/ipv6/ip6mr.c:124 RCU-list traversed in non-reader section!!
> 
> ipmr_new_table() returns an existing table, but there is no table at
> init. Therefore the condition: either holding rtnl or the list is empty
> is used.
> 
> Fixes: d1db275dd3f6e ("ipv6: ip6mr: support multiple tables")
> Reported-by: kernel test robot <lkp@intel.com>
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

Applied and queued up for -stable, thanks.
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, back to index

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-16  7:45 [Linux-kernel-mentees] [PATCH net v2] ipv6: Fix suspicious RCU usage warning in ip6mr madhuparnabhowmik10
2020-05-16 20:43 ` David Miller

Linux Kernel Mentees Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-kernel-mentees/0 linux-kernel-mentees/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-kernel-mentees linux-kernel-mentees/ https://lore.kernel.org/linux-kernel-mentees \
		linux-kernel-mentees@lists.linuxfoundation.org
	public-inbox-index linux-kernel-mentees

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linuxfoundation.lists.linux-kernel-mentees


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git