ipvs: move old_secure_tcp into struct netns_ipvs

syzbot reported the following issue :

BUG: KCSAN: data-race in update_defense_level / update_defense_level

read to 0xffffffff861a6260 of 4 bytes by task 3006 on cpu 1:
 update_defense_level+0x621/0xb30 net/netfilter/ipvs/ip_vs_ctl.c:177
 defense_work_handler+0x3d/0xd0 net/netfilter/ipvs/ip_vs_ctl.c:225
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffffffff861a6260 of 4 bytes by task 7333 on cpu 0:
 update_defense_level+0xa62/0xb30 net/netfilter/ipvs/ip_vs_ctl.c:205
 defense_work_handler+0x3d/0xd0 net/netfilter/ipvs/ip_vs_ctl.c:225
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7333 Comm: kworker/0:5 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events defense_work_handler

Indeed, old_secure_tcp is currently a static variable, while it
needs to be a per netns variable.

Fixes: a0840e2e165a ("IPVS: netns, ip_vs_ctl local vars moved to ipvs struct.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

2 files changed, 8 insertions, 8 deletions

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 3759167f91f5..078887c8c586 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -889,6 +889,7 @@ struct netns_ipvs {
         struct delayed_work     defense_work;   /* Work handler */
         int                     drop_rate;
         int                     drop_counter;
+        int                     old_secure_tcp;
         atomic_t                dropentry;
         /* locks in ctl.c */
         spinlock_t              dropentry_lock;  /* drop entry handling */
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index c8f81dd15c83..3cccc88ef817 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -93,7 +93,6 @@ static bool __ip_vs_addr_is_local_v6(struct net *net,
 static void update_defense_level(struct netns_ipvs *ipvs)
 {
         struct sysinfo i;
-        static int old_secure_tcp = 0;
         int availmem;
         int nomem;
         int to_change = -1;
@@ -174,35 +173,35 @@ static void update_defense_level(struct netns_ipvs *ipvs)
         spin_lock(&ipvs->securetcp_lock);
         switch (ipvs->sysctl_secure_tcp) {
         case 0:
-                if (old_secure_tcp >= 2)
+                if (ipvs->old_secure_tcp >= 2)
                         to_change = 0;
                 break;
         case 1:
                 if (nomem) {
-                        if (old_secure_tcp < 2)
+                        if (ipvs->old_secure_tcp < 2)
                                 to_change = 1;
                         ipvs->sysctl_secure_tcp = 2;
                 } else {
-                        if (old_secure_tcp >= 2)
+                        if (ipvs->old_secure_tcp >= 2)
                                 to_change = 0;
                 }
                 break;
         case 2:
                 if (nomem) {
-                        if (old_secure_tcp < 2)
+                        if (ipvs->old_secure_tcp < 2)
                                 to_change = 1;
                 } else {
-                        if (old_secure_tcp >= 2)
+                        if (ipvs->old_secure_tcp >= 2)
                                 to_change = 0;
                         ipvs->sysctl_secure_tcp = 1;
                 }
                 break;
         case 3:
-                if (old_secure_tcp < 2)
+                if (ipvs->old_secure_tcp < 2)
                         to_change = 1;
                 break;
         }
-        old_secure_tcp = ipvs->sysctl_secure_tcp;
+        ipvs->old_secure_tcp = ipvs->sysctl_secure_tcp;
         if (to_change >= 0)
                 ip_vs_protocol_timeout_change(ipvs,
                                               ipvs->sysctl_secure_tcp > 1);