From: Eric Dumazet <edumazet@google.com> mainline inclusion from mainline-v7.2-rc1 commit 8eed5519e496b7a07f441a0f579cb228a33189f7 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/17648 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Blamed commit converted the untracked dev_hold()/dev_put() calls in the watchdog code to use the tracked dev_hold_track()/dev_put_track() (which were later renamed/interfaced to netdev_hold() and netdev_put()). By introducing dev->watchdog_dev_tracker to store the reference tracking information without adding synchronization between netdev_watchdog_up() and dev_watchdog(), it enabled the race condition where this pointer could be overwritten or freed concurrently, leading to the list corruption crash syzbot reported: list_del corruption, ffff888114a18c00->next is NULL kernel BUG at lib/list_debug.c:52 ! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 91 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound linkwatch_event RIP: 0010:__list_del_entry_valid_or_report.cold+0x22/0x2a lib/list_debug.c:52 Call Trace: <TASK> __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_move_tail include/linux/list.h:341 [inline] ref_tracker_free+0x1a7/0x6c0 lib/ref_tracker.c:329 netdev_tracker_free include/linux/netdevice.h:4491 [inline] netdev_put include/linux/netdevice.h:4508 [inline] netdev_put include/linux/netdevice.h:4504 [inline] netdev_watchdog_down net/sched/sch_generic.c:600 [inline] dev_deactivate_many+0x28c/0xfe0 net/sched/sch_generic.c:1363 dev_deactivate+0x109/0x1d0 net/sched/sch_generic.c:1397 linkwatch_do_dev net/core/link_watch.c:184 [inline] linkwatch_do_dev+0xd3/0x120 net/core/link_watch.c:166 __linkwatch_run_queue+0x3a5/0x810 net/core/link_watch.c:240 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:314 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 This patch has three coordinated parts: 1) Add dev->watchdog_lock and dev->watchdog_ref_held to serialize watchdog operations. 2) Remove netdev_watchdog_up() call from netif_carrier_on(): This ensures netdev_watchdog_up() is only called from process/BH context (via linkwatch workqueue dev_activate()), allowing us to use spin_lock_bh() for synchronization. 3) Synchronize watchdog up and watchdog timer: Protect netdev_watchdog_up() with tx_global_lock and watchdog_lock. Only allocate a new tracker in netdev_watchdog_up() if one is not already present. In dev_watchdog(), ensure we don't release the tracker if the timer was rescheduled either by dev_watchdog() itself or concurrently by netdev_watchdog_up(). Fixes: f12bf6f3f942 ("net: watchdog: add net device refcount tracker") Reported-by: syzbot+381d82bbf0253710b35d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a26b751.c25708ab.1b19ef.0013.GAE@google.com/... Tested-by: syzbot+3479efbc2821cb2a79f2@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20260611152737.2580480-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/sched/sch_generic.c [8fa7292fee5c ("treewide: Switch/rename to timer_delete[_sync]()") is not merged.] Signed-off-by: JiangJieHua <jiangjiehua1@huawei.com> --- include/linux/netdevice.h | 4 ++++ net/core/dev.c | 3 ++- net/sched/sch_generic.c | 44 +++++++++++++++++++++++++++++---------- 3 files changed, 39 insertions(+), 12 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index a57fb36c6c1d3..f50d39af3edbf 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1986,6 +1986,8 @@ enum netdev_stat_type { * @qdisc_hash: qdisc hash table * @watchdog_timeo: Represents the timeout that is used by * the watchdog (see dev_watchdog()) + * @watchdog_lock: protect watchdog_ref_held + * @watchdog_ref_held: True if the watchdog device ref is taken. * @watchdog_timer: List of timers * * @proto_down_reason: reason a netdev interface is held down @@ -2329,6 +2331,8 @@ struct net_device { /* These may be needed for future network-power-down code. */ struct timer_list watchdog_timer; int watchdog_timeo; + spinlock_t watchdog_lock; + bool watchdog_ref_held; u32 proto_down_reason; diff --git a/net/core/dev.c b/net/core/dev.c index 990238824764a..f6188d2ac8b46 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10280,7 +10280,8 @@ static int netif_alloc_netdev_queues(struct net_device *dev) netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL); spin_lock_init(&dev->tx_global_lock); - + spin_lock_init(&dev->watchdog_lock); + dev->watchdog_ref_held = false; return 0; } diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 158067a798213..6b0125206c048 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -541,16 +541,24 @@ static void dev_watchdog(struct timer_list *t) dev->netdev_ops->ndo_tx_timeout(dev, i); netif_unfreeze_queues(dev); } - if (!mod_timer(&dev->watchdog_timer, - round_jiffies(oldest_start + - dev->watchdog_timeo))) - release = false; + spin_lock(&dev->watchdog_lock); + mod_timer(&dev->watchdog_timer, + round_jiffies(oldest_start + + dev->watchdog_timeo)); + release = false; + spin_unlock(&dev->watchdog_lock); } } spin_unlock(&dev->tx_global_lock); - if (release) + spin_lock(&dev->watchdog_lock); + if (timer_pending(&dev->watchdog_timer)) + release = false; + if (release && dev->watchdog_ref_held) { netdev_put(dev, &dev->watchdog_dev_tracker); + dev->watchdog_ref_held = false; + } + spin_unlock(&dev->watchdog_lock); } void netdev_watchdog_up(struct net_device *dev) @@ -559,18 +567,34 @@ void netdev_watchdog_up(struct net_device *dev) return; if (dev->watchdog_timeo <= 0) dev->watchdog_timeo = 5*HZ; + spin_lock_bh(&dev->tx_global_lock); + + spin_lock(&dev->watchdog_lock); if (!mod_timer(&dev->watchdog_timer, - round_jiffies(jiffies + dev->watchdog_timeo))) - netdev_hold(dev, &dev->watchdog_dev_tracker, - GFP_ATOMIC); + round_jiffies(jiffies + dev->watchdog_timeo))) { + if (!dev->watchdog_ref_held) { + netdev_hold(dev, &dev->watchdog_dev_tracker, + GFP_ATOMIC); + dev->watchdog_ref_held = true; + } + } + spin_unlock(&dev->watchdog_lock); + + spin_unlock_bh(&dev->tx_global_lock); } EXPORT_SYMBOL_GPL(netdev_watchdog_up); static void netdev_watchdog_down(struct net_device *dev) { netif_tx_lock_bh(dev); - if (del_timer(&dev->watchdog_timer)) + + spin_lock(&dev->watchdog_lock); + if (del_timer(&dev->watchdog_timer)) { netdev_put(dev, &dev->watchdog_dev_tracker); + dev->watchdog_ref_held = false; + } + spin_unlock(&dev->watchdog_lock); + netif_tx_unlock_bh(dev); } @@ -587,8 +611,6 @@ void netif_carrier_on(struct net_device *dev) return; atomic_inc(&dev->carrier_up_count); linkwatch_fire_event(dev); - if (netif_running(dev)) - netdev_watchdog_up(dev); } } EXPORT_SYMBOL(netif_carrier_on); -- 2.33.8