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![Davide Caratti](/assets/img/avatar_default.png)
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>
250 lines
5.6 KiB
C
250 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS An implementation of the IP virtual server support for the
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* LINUX operating system. IPVS is now implemented as a module
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* over the Netfilter framework. IPVS can be used to build a
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* high-performance and highly available server based on a
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* cluster of servers.
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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* Peter Kese <peter.kese@ijs.si>
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*
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* Changes:
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*/
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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/interrupt.h>
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#include <asm/string.h>
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#include <linux/kmod.h>
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#include <linux/sysctl.h>
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#include <net/ip_vs.h>
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EXPORT_SYMBOL(ip_vs_scheduler_err);
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/*
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* IPVS scheduler list
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*/
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static LIST_HEAD(ip_vs_schedulers);
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/* semaphore for schedulers */
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static DEFINE_MUTEX(ip_vs_sched_mutex);
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/*
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* Bind a service with a scheduler
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*/
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int ip_vs_bind_scheduler(struct ip_vs_service *svc,
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struct ip_vs_scheduler *scheduler)
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{
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int ret;
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if (scheduler->init_service) {
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ret = scheduler->init_service(svc);
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if (ret) {
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pr_err("%s(): init error\n", __func__);
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return ret;
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}
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}
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rcu_assign_pointer(svc->scheduler, scheduler);
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return 0;
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}
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/*
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* Unbind a service with its scheduler
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*/
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void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
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struct ip_vs_scheduler *sched)
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{
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struct ip_vs_scheduler *cur_sched;
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cur_sched = rcu_dereference_protected(svc->scheduler, 1);
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/* This check proves that old 'sched' was installed */
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if (!cur_sched)
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return;
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if (sched->done_service)
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sched->done_service(svc);
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/* svc->scheduler can be set to NULL only by caller */
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}
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/*
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* Get scheduler in the scheduler list by name
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*/
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static struct ip_vs_scheduler *ip_vs_sched_getbyname(const char *sched_name)
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{
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struct ip_vs_scheduler *sched;
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IP_VS_DBG(2, "%s(): sched_name \"%s\"\n", __func__, sched_name);
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mutex_lock(&ip_vs_sched_mutex);
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list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
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/*
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* Test and get the modules atomically
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*/
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if (sched->module && !try_module_get(sched->module)) {
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/*
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* This scheduler is just deleted
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*/
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continue;
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}
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if (strcmp(sched_name, sched->name)==0) {
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/* HIT */
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mutex_unlock(&ip_vs_sched_mutex);
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return sched;
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}
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module_put(sched->module);
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}
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mutex_unlock(&ip_vs_sched_mutex);
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return NULL;
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}
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/*
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* Lookup scheduler and try to load it if it doesn't exist
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*/
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struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
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{
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struct ip_vs_scheduler *sched;
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/*
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* Search for the scheduler by sched_name
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*/
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sched = ip_vs_sched_getbyname(sched_name);
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/*
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* If scheduler not found, load the module and search again
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*/
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if (sched == NULL) {
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request_module("ip_vs_%s", sched_name);
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sched = ip_vs_sched_getbyname(sched_name);
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}
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return sched;
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}
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void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler)
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{
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if (scheduler)
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module_put(scheduler->module);
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}
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/*
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* Common error output helper for schedulers
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*/
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void ip_vs_scheduler_err(struct ip_vs_service *svc, const char *msg)
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{
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struct ip_vs_scheduler *sched = rcu_dereference(svc->scheduler);
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char *sched_name = sched ? sched->name : "none";
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if (svc->fwmark) {
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IP_VS_ERR_RL("%s: FWM %u 0x%08X - %s\n",
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sched_name, svc->fwmark, svc->fwmark, msg);
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#ifdef CONFIG_IP_VS_IPV6
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} else if (svc->af == AF_INET6) {
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IP_VS_ERR_RL("%s: %s [%pI6c]:%d - %s\n",
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sched_name, ip_vs_proto_name(svc->protocol),
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&svc->addr.in6, ntohs(svc->port), msg);
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#endif
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} else {
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IP_VS_ERR_RL("%s: %s %pI4:%d - %s\n",
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sched_name, ip_vs_proto_name(svc->protocol),
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&svc->addr.ip, ntohs(svc->port), msg);
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}
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}
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/*
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* Register a scheduler in the scheduler list
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*/
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int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
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{
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struct ip_vs_scheduler *sched;
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if (!scheduler) {
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pr_err("%s(): NULL arg\n", __func__);
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return -EINVAL;
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}
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if (!scheduler->name) {
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pr_err("%s(): NULL scheduler_name\n", __func__);
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return -EINVAL;
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}
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/* increase the module use count */
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if (!ip_vs_use_count_inc())
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return -ENOENT;
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mutex_lock(&ip_vs_sched_mutex);
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if (!list_empty(&scheduler->n_list)) {
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mutex_unlock(&ip_vs_sched_mutex);
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ip_vs_use_count_dec();
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pr_err("%s(): [%s] scheduler already linked\n",
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__func__, scheduler->name);
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return -EINVAL;
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}
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/*
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* Make sure that the scheduler with this name doesn't exist
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* in the scheduler list.
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*/
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list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
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if (strcmp(scheduler->name, sched->name) == 0) {
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mutex_unlock(&ip_vs_sched_mutex);
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ip_vs_use_count_dec();
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pr_err("%s(): [%s] scheduler already existed "
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"in the system\n", __func__, scheduler->name);
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return -EINVAL;
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}
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}
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/*
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* Add it into the d-linked scheduler list
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*/
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list_add(&scheduler->n_list, &ip_vs_schedulers);
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mutex_unlock(&ip_vs_sched_mutex);
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pr_info("[%s] scheduler registered.\n", scheduler->name);
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return 0;
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}
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/*
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* Unregister a scheduler from the scheduler list
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*/
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int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
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{
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if (!scheduler) {
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pr_err("%s(): NULL arg\n", __func__);
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return -EINVAL;
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}
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mutex_lock(&ip_vs_sched_mutex);
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if (list_empty(&scheduler->n_list)) {
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mutex_unlock(&ip_vs_sched_mutex);
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pr_err("%s(): [%s] scheduler is not in the list. failed\n",
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__func__, scheduler->name);
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return -EINVAL;
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}
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/*
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* Remove it from the d-linked scheduler list
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*/
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list_del(&scheduler->n_list);
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mutex_unlock(&ip_vs_sched_mutex);
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/* decrease the module use count */
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ip_vs_use_count_dec();
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pr_info("[%s] scheduler unregistered.\n", scheduler->name);
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return 0;
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}
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