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authorAmol Grover2020-05-14 23:31:03 +0530
committerDavid S. Miller2020-05-14 18:01:07 -0700
commit7013908c2db285cd6b48fcd427a56354beac2233 (patch)
tree6d400465a8018a4178d60deb595baa2b80b5ca4c /net/ipv4
parenta14fbcd4f157a5a97b6013289205559d246c5021 (diff)
ipmr: Add lockdep expression to ipmr_for_each_table macro
During the initialization process, ipmr_new_table() is called to create new tables which in turn calls ipmr_get_table() which traverses net->ipv4.mr_tables without holding the writer lock. However, this is safe to do so as no tables exist at this time. Hence add a suitable lockdep expression to silence the following false-positive warning: ============================= WARNING: suspicious RCU usage 5.7.0-rc3-next-20200428-syzkaller #0 Not tainted ----------------------------- net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!! ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136 ipmr_new_table net/ipv4/ipmr.c:403 [inline] ipmr_rules_init net/ipv4/ipmr.c:248 [inline] ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089 Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables") Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com Suggested-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Amol Grover <frextrite@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ipmr.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 4897f7420c8f..5c218db2dede 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
- lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net) \
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held() || \
+ list_empty(&net->ipv4.mr_tables))
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)