[PATCH 3.16 090/136] ipvs: move old_secure_tcp into struct netns_ipvs

Ben Hutchings
2019-12-17T00:54:01Z

From: Eric Dumazet <edumazet@google.com>

commit c24b75e0f9239e78105f81c5f03a751641eb07ef upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/net/ip_vs.h | 1 +
net/netfilter/ipvs/ip_vs_ctl.c | 15 +++++++--------
2 files changed, 8 insertions(+), 8 deletions(-)

--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -919,6 +919,7 @@ 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 */
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -97,7 +97,6 @@ static bool __ip_vs_addr_is_local_v6(str
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;
@@ -178,35 +177,35 @@ static void update_defense_level(struct
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);