From: Davide Caratti dcaratti@redhat.com
[ Upstream commit 62931f59ce9cbabb934a431f48f2f1f441c605ac ]
if the IPVS module is removed while the sync daemon is starting, there is a small gap where try_module_get() might fail getting the refcount inside ip_vs_use_count_inc(). Then, the refcounts of IPVS module are unbalanced, and the subsequent call to stop_sync_thread() causes the following splat:
WARNING: CPU: 0 PID: 4013 at kernel/module.c:1146 module_put.part.44+0x15b/0x290 Modules linked in: ip_vs(-) nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 veth ip6table_filter ip6_tables iptable_filter binfmt_misc intel_rapl_msr intel_rapl_common crct10dif_pclmul crc32_pclmul ext4 mbcache jbd2 ghash_clmulni_intel snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_nhlt snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd cryptd glue_helper joydev pcspkr snd_timer virtio_balloon snd soundcore i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi virtio_net net_failover virtio_blk failover virtio_console qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ata_piix ttm crc32c_intel serio_raw drm virtio_pci libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: nf_defrag_ipv6] CPU: 0 PID: 4013 Comm: modprobe Tainted: G W 5.4.0-rc1.upstream+ #741 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:module_put.part.44+0x15b/0x290 Code: 04 25 28 00 00 00 0f 85 18 01 00 00 48 83 c4 68 5b 5d 41 5c 41 5d 41 5e 41 5f c3 89 44 24 28 83 e8 01 89 c5 0f 89 57 ff ff ff <0f> 0b e9 78 ff ff ff 65 8b 1d 67 83 26 4a 89 db be 08 00 00 00 48 RSP: 0018:ffff888050607c78 EFLAGS: 00010297 RAX: 0000000000000003 RBX: ffffffffc1420590 RCX: ffffffffb5db0ef9 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffffc1420590 RBP: 00000000ffffffff R08: fffffbfff82840b3 R09: fffffbfff82840b3 R10: 0000000000000001 R11: fffffbfff82840b2 R12: 1ffff1100a0c0f90 R13: ffffffffc1420200 R14: ffff88804f533300 R15: ffff88804f533ca0 FS: 00007f8ea9720740(0000) GS:ffff888053800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3245abe000 CR3: 000000004c28a006 CR4: 00000000001606f0 Call Trace: stop_sync_thread+0x3a3/0x7c0 [ip_vs] ip_vs_sync_net_cleanup+0x13/0x50 [ip_vs] ops_exit_list.isra.5+0x94/0x140 unregister_pernet_operations+0x29d/0x460 unregister_pernet_device+0x26/0x60 ip_vs_cleanup+0x11/0x38 [ip_vs] __x64_sys_delete_module+0x2d5/0x400 do_syscall_64+0xa5/0x4e0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f8ea8bf0db7 Code: 73 01 c3 48 8b 0d b9 80 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 89 80 2c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffcd38d2fe8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 RAX: ffffffffffffffda RBX: 0000000002436240 RCX: 00007f8ea8bf0db7 RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00000000024362a8 RBP: 0000000000000000 R08: 00007f8ea8eba060 R09: 00007f8ea8c658a0 R10: 00007ffcd38d2a60 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000001 R14: 00000000024362a8 R15: 0000000000000000 irq event stamp: 4538 hardirqs last enabled at (4537): [<ffffffffb6193dde>] quarantine_put+0x9e/0x170 hardirqs last disabled at (4538): [<ffffffffb5a0556a>] trace_hardirqs_off_thunk+0x1a/0x20 softirqs last enabled at (4522): [<ffffffffb6f8ebe9>] sk_common_release+0x169/0x2d0 softirqs last disabled at (4520): [<ffffffffb6f8eb3e>] sk_common_release+0xbe/0x2d0
Check the return value of ip_vs_use_count_inc() and let its caller return proper error. Inside do_ip_vs_set_ctl() the module is already refcounted, we don't need refcount/derefcount there. Finally, in register_ip_vs_app() and start_sync_thread(), take the module refcount earlier and ensure it's released in the error path.
Change since v1: - better return values in case of failure of ip_vs_use_count_inc(), thanks to Julian Anastasov - no need to increase/decrease the module refcount in ip_vs_set_ctl(), thanks to Julian Anastasov
Signed-off-by: Davide Caratti dcaratti@redhat.com Signed-off-by: Julian Anastasov ja@ssi.bg Signed-off-by: Simon Horman horms@verge.net.au Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/ipvs/ip_vs_app.c | 12 ++++++++++-- net/netfilter/ipvs/ip_vs_ctl.c | 14 ++++---------- net/netfilter/ipvs/ip_vs_pe.c | 3 ++- net/netfilter/ipvs/ip_vs_sched.c | 3 ++- net/netfilter/ipvs/ip_vs_sync.c | 13 ++++++++++--- 5 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_app.c b/net/netfilter/ipvs/ip_vs_app.c index 4515056ef1c2b..f9b16f2b22191 100644 --- a/net/netfilter/ipvs/ip_vs_app.c +++ b/net/netfilter/ipvs/ip_vs_app.c @@ -193,21 +193,29 @@ struct ip_vs_app *register_ip_vs_app(struct netns_ipvs *ipvs, struct ip_vs_app *
mutex_lock(&__ip_vs_app_mutex);
+ /* increase the module use count */ + if (!ip_vs_use_count_inc()) { + err = -ENOENT; + goto out_unlock; + } + list_for_each_entry(a, &ipvs->app_list, a_list) { if (!strcmp(app->name, a->name)) { err = -EEXIST; + /* decrease the module use count */ + ip_vs_use_count_dec(); goto out_unlock; } } a = kmemdup(app, sizeof(*app), GFP_KERNEL); if (!a) { err = -ENOMEM; + /* decrease the module use count */ + ip_vs_use_count_dec(); goto out_unlock; } INIT_LIST_HEAD(&a->incs_list); list_add(&a->a_list, &ipvs->app_list); - /* increase the module use count */ - ip_vs_use_count_inc();
out_unlock: mutex_unlock(&__ip_vs_app_mutex); diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 060565e7d227a..248c76290116e 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -1275,7 +1275,8 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u, struct ip_vs_service *svc = NULL;
/* increase the module use count */ - ip_vs_use_count_inc(); + if (!ip_vs_use_count_inc()) + return -ENOPROTOOPT;
/* Lookup the scheduler by 'u->sched_name' */ if (strcmp(u->sched_name, "none")) { @@ -2434,9 +2435,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) if (copy_from_user(arg, user, len) != 0) return -EFAULT;
- /* increase the module use count */ - ip_vs_use_count_inc(); - /* Handle daemons since they have another lock */ if (cmd == IP_VS_SO_SET_STARTDAEMON || cmd == IP_VS_SO_SET_STOPDAEMON) { @@ -2449,13 +2447,13 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) ret = -EINVAL; if (strscpy(cfg.mcast_ifn, dm->mcast_ifn, sizeof(cfg.mcast_ifn)) <= 0) - goto out_dec; + return ret; cfg.syncid = dm->syncid; ret = start_sync_thread(ipvs, &cfg, dm->state); } else { ret = stop_sync_thread(ipvs, dm->state); } - goto out_dec; + return ret; }
mutex_lock(&__ip_vs_mutex); @@ -2550,10 +2548,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
out_unlock: mutex_unlock(&__ip_vs_mutex); - out_dec: - /* decrease the module use count */ - ip_vs_use_count_dec(); - return ret; }
diff --git a/net/netfilter/ipvs/ip_vs_pe.c b/net/netfilter/ipvs/ip_vs_pe.c index 8e104dff7abc4..166c669f07634 100644 --- a/net/netfilter/ipvs/ip_vs_pe.c +++ b/net/netfilter/ipvs/ip_vs_pe.c @@ -68,7 +68,8 @@ int register_ip_vs_pe(struct ip_vs_pe *pe) struct ip_vs_pe *tmp;
/* increase the module use count */ - ip_vs_use_count_inc(); + if (!ip_vs_use_count_inc()) + return -ENOENT;
mutex_lock(&ip_vs_pe_mutex); /* Make sure that the pe with this name doesn't exist diff --git a/net/netfilter/ipvs/ip_vs_sched.c b/net/netfilter/ipvs/ip_vs_sched.c index 2f9d5cd5daeee..d4903723be7e9 100644 --- a/net/netfilter/ipvs/ip_vs_sched.c +++ b/net/netfilter/ipvs/ip_vs_sched.c @@ -179,7 +179,8 @@ int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler) }
/* increase the module use count */ - ip_vs_use_count_inc(); + if (!ip_vs_use_count_inc()) + return -ENOENT;
mutex_lock(&ip_vs_sched_mutex);
diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c index a4a78c4b06dec..8dc892a9dc91a 100644 --- a/net/netfilter/ipvs/ip_vs_sync.c +++ b/net/netfilter/ipvs/ip_vs_sync.c @@ -1762,6 +1762,10 @@ int start_sync_thread(struct netns_ipvs *ipvs, struct ipvs_sync_daemon_cfg *c, IP_VS_DBG(7, "Each ip_vs_sync_conn entry needs %zd bytes\n", sizeof(struct ip_vs_sync_conn_v0));
+ /* increase the module use count */ + if (!ip_vs_use_count_inc()) + return -ENOPROTOOPT; + /* Do not hold one mutex and then to block on another */ for (;;) { rtnl_lock(); @@ -1892,9 +1896,6 @@ int start_sync_thread(struct netns_ipvs *ipvs, struct ipvs_sync_daemon_cfg *c, mutex_unlock(&ipvs->sync_mutex); rtnl_unlock();
- /* increase the module use count */ - ip_vs_use_count_inc(); - return 0;
out: @@ -1924,11 +1925,17 @@ out: } kfree(ti); } + + /* decrease the module use count */ + ip_vs_use_count_dec(); return result;
out_early: mutex_unlock(&ipvs->sync_mutex); rtnl_unlock(); + + /* decrease the module use count */ + ip_vs_use_count_dec(); return result; }