Improper Locking

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen() l2cap_chan_close() removes the channel from conn->chan_l, which must be done under conn->lock. cleanup_listen() runs under the parent sk_lock, so acquiring conn->lock would invert the established conn->lock -> chan->lock -> sk_lock order. Instead of calling l2cap_chan_close() directly, schedule l2cap_chan_timeout with delay 0 to close the channel asynchronously. The timeout handler already acquires conn->lock and chan->lock in the correct order. The timer is only armed when chan->conn is still set: if it is already NULL, l2cap_conn_del() has already processed this channel (l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb), so there is nothing left to do. If l2cap_conn_del() races in after the timer is armed, __clear_chan_timer() inside l2cap_chan_del() cancels it; if the timer has already fired, the handler returns harmlessly because chan->conn was cleared.Show less

The USB CDC-NCM device class (subsys/usb/device_next/class/usbd_cdc_ncm.c) ignores the return value of usbd_ep_enqueue() in its ethernet transmit callback cdc_ncm_send(). When the enqueue fails, the function still calls k_sem_take(&data->sync_sem, K_FOREVER), blocking on a completion semaphore that is only ever signaled from the bulk-IN transfer-completion callback. Because nothing was enqueued, that callback never fires and the calling thread — a shared network traffic-class TX thread — deadlocks permanently while holding the interface TX lock, halting transmission until reboot (and leaking the transmit buffer). The enqueue fails under conditions controlled by the attached USB host: usbd_ep_enqueue() returns -EPERM whenever the bus is suspended (a standard, persistent host operation), and the underlying udc_ep_enqueue() returns -EPERM/-ENODEV on disconnect, bus reset, or endpoint disable. The cdc_ncm_send() guard only checks the DATA_IFACE_ENABLED and IFACE_UP flags, not the suspended state, so a packet transmitted while the host holds the bus suspended reaches the failing enqueue and deadlocks the TX path. The realistic trigger is a bus suspend that occurs while the exported network interface is active and has traffic to send — host sleep, USB selective/auto-suspend, or hub power management — after which any device-originated packet deadlocks the path, recoverable only by reboot. The impact is a persistent loss of the virtual network connection between the host's NCM interface and the Zephyr device; because the deadlocked thread is a shared traffic-class TX thread, egress on other network interfaces can stall as well. There is no memory corruption or information disclosure. The defect was introduced with the CDC-NCM driver and shipped in releases through v4.4.0; it is fixed by checking the usbd_ep_enqueue() return value and freeing the buffer before the blocking wait.Show less

In the Linux kernel, the following vulnerability has been resolved: net: dsa: remove redundant netdev_lock_ops() from conduit ethtool ops DSA replaces the conduit (master) device's ethtool_ops with its own wrappers that aggregate stats from both the conduit and DSA switch ports. Taking the lock again inside the DSA wrappers causes a deadlock. Stumbled upon this when booting qemu with fbnic and CONFIG_NET_DSA_LOOP=y (which looks like some kind of testing device that auto-populates the ports of eth0). `ethtool -i` is enough to deadlock. This means we have basically zero coverage for DSA stuff with real ops locked devs. Remove the redundant netdev_lock_ops()/netdev_unlock_ops() calls from the DSA conduit ethtool wrappers.Show less

In the Linux kernel, the following vulnerability has been resolved: scsi: sg: Resolve soft lockup issue when opening /dev/sgX The parameter def_reserved_size defines the default buffer size reserved for each Sg_fd and should be restricted to a range between 0 and 1,048,576 (see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html). Although the function sg_proc_write_dressz enforces this limit, it is possible to bypass it by directly modifying the module parameter as shown below, which then causes a soft lockup: echo -1 > /sys/module/sg/parameters/def_reserved_size exec 4<> /dev/sg0 watchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537] Modules loaded: CPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134, PREEMPT disabled Hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version 1.16.1-2.fc37 dated 04/01/2014 ... Call Trace: sg_build_reserve+0x5c/0xa0 sg_add_sfp+0x168/0x270 sg_open+0x16e/0x340 chrdev_open+0xbe/0x230 do_dentry_open+0x175/0x480 vfs_open+0x34/0xf0 do_open+0x265/0x3d0 path_openat+0x110/0x290 do_filp_open+0xc3/0x170 do_sys_openat2+0x71/0xe0 __x64_sys_openat+0x6d/0xa0 do_syscall_64+0x62/0x310 entry_SYSCALL_64_after_hwframe+0x76/0x7e The fix is to use module_param_cb to validate and reject invalid values assigned to def_reserved_size.Show less

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: fix AMDGPU_INFO_READ_MMR_REG There were multiple issues in that code. First of all the order between the reset semaphore and the mm_lock was wrong (e.g. copy_to_user) was called while holding the lock. Then we allocated memory while holding the reset semaphore which is also a pretty big bug and can deadlock. Then we used down_read_trylock() instead of waiting for the reset to finish. (cherry picked from commit 361b6e6b303d4b691f6c5974d3eaab67ca6dd90e)Show less

In the Linux kernel, the following vulnerability has been resolved: net: phy: don't try to setup PHY-driven SFP cages when using genphy We don't have support for PHY-driver SFP cages with the genphy code. On top of that, it was found by sashiko that running sfp_bus_add_upstream() for genphy deadlocks, as for genphy the PHY probing runs under RTNL, which isn't the case for non-genphy drivers. This problem was reproduced, and does lead to a deadlock on RTNL. Before the blamed commit, the phy_sfp_probe() call was made by individual PHY drivers, so there was no way to get to the SFP probing path when using genphy. Let's therefore only run phy_sfp_probe when not using genphy.Show less

In the Linux kernel, the following vulnerability has been resolved: mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison Two concurrent madvise(MADV_HWPOISON) calls on the same hugetlb page can trigger a recursive spinlock self-deadlock (AA deadlock) on hugetlb_lock when racing with a concurrent unmap: thread#0 thread#1 -------- -------- madvise(folio, MADV_HWPOISON) -> poisons the folio successfully madvise(folio, MADV_HWPOISON) unmap(folio) try_memory_failure_hugetlb get_huge_page_for_hwpoison spin_lock_irq(&hugetlb_lock) <- held __get_huge_page_for_hwpoison hugetlb_update_hwpoison() -> MF_HUGETLB_FOLIO_PRE_POISONED goto out: folio_put() refcount: 1 -> 0 free_huge_folio() spin_lock_irqsave(&hugetlb_lock) -> AA DEADLOCK! The out: path in __get_huge_page_for_hwpoison() calls folio_put() to drop the GUP reference while the hugetlb_lock is still held by the hugetlb.c wrapper get_huge_page_for_hwpoison(). If concurrent unmap has released the page table mapping reference, folio_put() drops the folio refcount to zero, triggering free_huge_folio() which attempts to re-acquire the non-recursive hugetlb_lock. Fix this by moving hugetlb_lock acquisition from the hugetlb.c wrapper into get_huge_page_for_hwpoison(). Place spin_unlock_irq() before the folio_put() at the out: label so the folio is always released outside the lock. [akpm@linux-foundation.org: fix race, rename label per Miaohe]Show less

In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: fix ABBA deadlock in iptfs_destroy_state() iptfs_destroy_state() calls hrtimer_cancel() while holding a spinlock that the timer callback also acquires, leading to an ABBA deadlock on SMP systems. For the output timer (iptfs_timer): - iptfs_destroy_state() holds x->lock, calls hrtimer_cancel() - iptfs_delay_timer() callback takes x->lock For the drop timer (drop_timer): - iptfs_destroy_state() holds drop_lock, calls hrtimer_cancel() - iptfs_drop_timer() callback takes drop_lock Both timers use HRTIMER_MODE_REL_SOFT, so their callbacks run in softirq context. When hrtimer_cancel() is called for a soft timer that is currently executing on another CPU, hrtimer_cancel_wait_running() spins on softirq_expiry_lock -- the same lock held by the softirq running the callback. If the callback is blocked waiting for the spinlock held by the caller of hrtimer_cancel(), a circular dependency forms: CPU 0: holds lock_A -> waits for softirq_expiry_lock CPU 1: holds softirq_expiry_lock -> waits for lock_A Fix by calling hrtimer_cancel() before acquiring the respective locks. hrtimer_cancel() is safe to call without holding any lock and will wait for any in-progress callback to complete. For the output timer, the lock is still acquired afterwards to drain the packet queue. For the drop timer, the lock/unlock pair is removed entirely since it only existed to serialize with the timer callback, which hrtimer_cancel() already guarantees. Found by source code audit.Show less

In the Linux kernel, the following vulnerability has been resolved: timers/migration: Fix livelock in tmigr_handle_remote_up() tmigr_handle_remote_cpu() skips timer_expire_remote() when cpu == smp_processor_id(), assuming the local softirq path already handled this CPU's timers. This assumption is wrong because jiffies can advance after the handling of the CPU's global timers in run_timer_base(BASE_GLOBAL) and before tmigr_handle_remote() evaluates the expiry times. As a consequence a timer which expires after the CPU local timer wheel advanced and becomes expired in the remote handling is ignored and the callback is never invoked and removed from the timer wheel. What's worse is that fetch_next_timer_interrupt_remote() keeps reporting it as expired, and the event is re-queued with expires == now on each iteration. The goto-again loop spins indefinitely. Fix this by calling timer_expire_remote() unconditionally. That's minimal overhead for the common case as __run_timer_base() returns immediately if there is nothing to expire in the local wheel. [ tglx: Amend change log and add a comment ]Show less

concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::ReadWriteLock#release_write_lock does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can then enter its critical section while the first writer is still running. Concurrent::ReadWriteLock#release_read_lock also decrements the shared counter even when no read lock is held. Calling it on a fresh lock changes the counter from 0 to -1, after which normal read acquisition raises Concurrent::ResourceLimitError. This is a synchronization correctness issue in the public Concurrent::ReadWriteLock API. This vulnerability is fixed in 1.3.7.Show less

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7925: fix potential deadlock in mt7925_roc_abort_sync roc_abort_sync() can deadlock with roc_work(). roc_work() holds dev->mt76.mutex, while cancel_work_sync() waits for roc_work() to finish. If the caller already owns the same mutex, both sides block and no progress is possible. This deadlock can occur during station removal when mt76_sta_state() -> mt76_sta_remove() -> mt7925_mac_sta_remove_link() -> mt7925_mac_link_sta_remove() -> mt7925_roc_abort_sync() invokes cancel_work_sync() while roc_work() is still running and holding dev->mt76.mutex. This avoids the mutex deadlock and preserves exactly-once work ownership.Show less

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7921: fix potential deadlock in mt7921_roc_abort_sync roc_abort_sync() can deadlock with roc_work(). roc_work() holds dev->mt76.mutex, while cancel_work_sync() waits for roc_work() to finish. If the caller already owns the same mutex, both sides block and no progress is possible. This deadlock can occur during station removal when mt76_sta_state() -> mt76_sta_remove() -> mt7921_mac_sta_remove() -> mt7921_roc_abort_sync() invokes cancel_work_sync() while roc_work() is still running and holding dev->mt76.mutex. This avoids the mutex deadlock and preserves exactly-once work ownership.Show less

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: fix deadlock in remain-on-channel mt76_remain_on_channel() and mt76_roc_complete() call mt76_set_channel() while already holding dev->mutex. Since mt76_set_channel() also acquires dev->mutex, this results in a deadlock. Use __mt76_set_channel() instead of mt76_set_channel(). Add cancel_delayed_work_sync() for mac_work before acquiring the mutex in mt76_remain_on_channel() to prevent a secondary deadlock with the mac_work workqueue.Show less

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: fix locking in hci_conn_request_evt() with HCI_PROTO_DEFER When protocol sets HCI_PROTO_DEFER, hci_conn_request_evt() calls hci_connect_cfm(conn) without hdev->lock. Generally hci_connect_cfm() assumes it is held, and if conn is deleted concurrently -> UAF. Only SCO and ISO set HCI_PROTO_DEFER and only for defer setup listen, and HCI_EV_CONN_REQUEST is not generated for ISO. In the non-deferred listening socket code paths, hci_connect_cfm(conn) is called with hdev->lock held. Fix by holding the lock.Show less

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: l2cap: Add missing chan lock in l2cap_ecred_reconf_rsp l2cap_ecred_reconf_rsp() calls l2cap_chan_del() without holding l2cap_chan_lock(). Every other l2cap_chan_del() caller in the file acquires the lock first. A remote BLE device can send a crafted L2CAP ECRED reconfiguration response to corrupt the channel list while another thread is iterating it. Add l2cap_chan_hold() and l2cap_chan_lock() before l2cap_chan_del(), and l2cap_chan_unlock() and l2cap_chan_put() after, matching the pattern used in l2cap_ecred_conn_rsp() and l2cap_conn_del().Show less

In the Linux kernel, the following vulnerability has been resolved: dm cache policy smq: fix missing locks in invalidating cache blocks In passthrough mode, the policy invalidate_mapping operation is called simultaneously from multiple workers, thus it should be protected by a lock. Otherwise, we might end up with data races on the allocated blocks counter, or even use-after-free issues with internal data structures when doing concurrent writes. Note that the existing FIXME in smq_invalidate_mapping() doesn't affect passthrough mode since migration tasks don't exist there, but would need attention if supporting fast device shrinking via suspend/resume without target reloading. Reproduce steps: 1. Create a cache device consisting of 1024 cache entries dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. Populate the cache, and record the number of cached blocks fio --name=populate --filename=/dev/mapper/cache --rw=randwrite --bs=4k \ --size=64m --direct=1 nr_cached=$(dmsetup status cache | awk '{split($7, a, "/"); print a[1]}') 3. Reload the cache into passthrough mode dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache 4. Write to the passthrough cache. By setting multiple jobs with I/O size equal to the cache block size, cache blocks are invalidated concurrently from different workers. fio --filename=/dev/mapper/cache --name=test --rw=randwrite --bs=64k \ --direct=1 --numjobs=2 --randrepeat=0 --size=64m 5. Check if demoted matches cached block count. These numbers should match but may differ due to the data race. nr_demoted=$(dmsetup status cache | awk '{print $12}') echo "$nr_cached, $nr_demoted"Show less

In the Linux kernel, the following vulnerability has been resolved: drm/msm: Fix VM_BIND UNMAP locking Wrong argument meant that the objs involved in UNMAP ops were not always getting locked. Since _NO_SHARE objs share a common resv with the VM (which is always locked) this would only show up with non-_NO_SHARE BOs. Patchwork: https://patchwork.freedesktop.org/patch/713898/Show less

In the Linux kernel, the following vulnerability has been resolved: gfs2: add some missing log locking Function gfs2_logd() calls the log flushing functions gfs2_ail1_start(), gfs2_ail1_wait(), and gfs2_ail1_empty() without holding sdp->sd_log_flush_lock, but these functions require exclusion against concurrent transactions. To fix that, add a non-locking __gfs2_log_flush() function. Then, in gfs2_logd(), take sdp->sd_log_flush_lock before calling the above mentioned log flushing functions and __gfs2_log_flush().Show less

In the Linux kernel, the following vulnerability has been resolved: HID: usbhid: fix deadlock in hid_post_reset() You can build a USB device that includes a HID component and a storage or UAS component. The components can be reset only together. That means that hid_pre_reset() and hid_post_reset() are in the block IO error handling. Hence no memory allocation used in them may do block IO because the IO can deadlock on the mutex held while resetting a device and calling the interface drivers. Use GFP_NOIO for all allocations in them.Show less

In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix af_unix iter deadlock bpf_iter_unix_seq_show() may deadlock when lock_sock_fast() takes the fast path and the iter prog attempts to update a sockmap. Which ends up spinning at sock_map_update_elem()'s bh_lock_sock(): WARNING: possible recursive locking detected test_progs/1393 is trying to acquire lock: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: sock_map_update_elem+0xdb/0x1f0 but task is already holding lock: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: __lock_sock_fast+0x37/0xe0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(slock-AF_UNIX); lock(slock-AF_UNIX); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by test_progs/1393: #0: ffff88814b59c790 (&p->lock){+.+.}-{4:4}, at: bpf_seq_read+0x59/0x10d0 #1: ffff88811ec25fd8 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: bpf_seq_read+0x42c/0x10d0 #2: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: __lock_sock_fast+0x37/0xe0 #3: ffffffff85a6a7c0 (rcu_read_lock){....}-{1:3}, at: bpf_iter_run_prog+0x51d/0xb00 Call Trace: dump_stack_lvl+0x5d/0x80 print_deadlock_bug.cold+0xc0/0xce __lock_acquire+0x130f/0x2590 lock_acquire+0x14e/0x2b0 _raw_spin_lock+0x30/0x40 sock_map_update_elem+0xdb/0x1f0 bpf_prog_2d0075e5d9b721cd_dump_unix+0x55/0x4f4 bpf_iter_run_prog+0x5b9/0xb00 bpf_iter_unix_seq_show+0x1f7/0x2e0 bpf_seq_read+0x42c/0x10d0 vfs_read+0x171/0xb20 ksys_read+0xff/0x200 do_syscall_64+0x6b/0x3a0 entry_SYSCALL_64_after_hwframe+0x76/0x7eShow less