Vulnerabilidades do Linux Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop Move the conditional loading of hardware DR6 with the guest's DR6 value out of the core .vcpu_run() loop to fix a bug where KVM can load hardware with a stale vcpu->arch.dr6. When the guest accesses a DR and host userspace isn't debugging the guest, KVM disables DR interception and loads the guest's values into hardware on VM-Enter and saves them on VM-Exit. This allows the guest to access DRs at will, e.g. so that a sequence of DR accesses to configure a breakpoint only generates one VM-Exit. For DR0-DR3, the logic/behavior is identical between VMX and SVM, and also identical between KVM_DEBUGREG_BP_ENABLED (userspace debugging the guest) and KVM_DEBUGREG_WONT_EXIT (guest using DRs), and so KVM handles loading DR0-DR3 in common code, _outside_ of the core kvm_x86_ops.vcpu_run() loop. But for DR6, the guest's value doesn't need to be loaded into hardware for KVM_DEBUGREG_BP_ENABLED, and SVM provides a dedicated VMCB field whereas VMX requires software to manually load the guest value, and so loading the guest's value into DR6 is handled by {svm,vmx}_vcpu_run(), i.e. is done _inside_ the core run loop. Unfortunately, saving the guest values on VM-Exit is initiated by common x86, again outside of the core run loop. If the guest modifies DR6 (in hardware, when DR interception is disabled), and then the next VM-Exit is a fastpath VM-Exit, KVM will reload hardware DR6 with vcpu->arch.dr6 and clobber the guest's actual value. The bug shows up primarily with nested VMX because KVM handles the VMX preemption timer in the fastpath, and the window between hardware DR6 being modified (in guest context) and DR6 being read by guest software is orders of magnitude larger in a nested setup. E.g. in non-nested, the VMX preemption timer would need to fire precisely between #DB injection and the #DB handler's read of DR6, whereas with a KVM-on-KVM setup, the window where hardware DR6 is "dirty" extends all the way from L1 writing DR6 to VMRESUME (in L1). L1's view: ========== <L1 disables DR interception> CPU 0/KVM-7289 [023] d.... 2925.640961: kvm_entry: vcpu 0 A: L1 Writes DR6 CPU 0/KVM-7289 [023] d.... 2925.640963: <hack>: Set DRs, DR6 = 0xffff0ff1 B: CPU 0/KVM-7289 [023] d.... 2925.640967: kvm_exit: vcpu 0 reason EXTERNAL_INTERRUPT intr_info 0x800000ec D: L1 reads DR6, arch.dr6 = 0 CPU 0/KVM-7289 [023] d.... 2925.640969: <hack>: Sync DRs, DR6 = 0xffff0ff0 CPU 0/KVM-7289 [023] d.... 2925.640976: kvm_entry: vcpu 0 L2 reads DR6, L1 disables DR interception CPU 0/KVM-7289 [023] d.... 2925.640980: kvm_exit: vcpu 0 reason DR_ACCESS info1 0x0000000000000216 CPU 0/KVM-7289 [023] d.... 2925.640983: kvm_entry: vcpu 0 CPU 0/KVM-7289 [023] d.... 2925.640983: <hack>: Set DRs, DR6 = 0xffff0ff0 L2 detects failure CPU 0/KVM-7289 [023] d.... 2925.640987: kvm_exit: vcpu 0 reason HLT L1 reads DR6 (confirms failure) CPU 0/KVM-7289 [023] d.... 2925.640990: <hack>: Sync DRs, DR6 = 0xffff0ff0 L0's view: ========== L2 reads DR6, arch.dr6 = 0 CPU 23/KVM-5046 [001] d.... 3410.005610: kvm_exit: vcpu 23 reason DR_ACCESS info1 0x0000000000000216 CPU 23/KVM-5046 [001] ..... 3410.005610: kvm_nested_vmexit: vcpu 23 reason DR_ACCESS info1 0x0000000000000216 L2 => L1 nested VM-Exit CPU 23/KVM-5046 [001] ..... 3410.005610: kvm_nested_vmexit_inject: reason: DR_ACCESS ext_inf1: 0x0000000000000216 CPU 23/KVM-5046 [001] d.... 3410.005610: kvm_entry: vcpu 23 CPU 23/KVM-5046 [001] d.... 3410.005611: kvm_exit: vcpu 23 reason VMREAD CPU 23/KVM-5046 [001] d.... 3410.005611: kvm_entry: vcpu 23 CPU 23/KVM-5046 [001] d.... 3410. ---truncated---

In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: reallocate buf lists on upgrade IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: core: flush gadget workqueue after device removal device_del() can lead to new work being scheduled in gadget->work workqueue. This is observed, for example, with the dwc3 driver with the following call stack: device_del() gadget_unbind_driver() usb_gadget_disconnect_locked() dwc3_gadget_pullup() dwc3_gadget_soft_disconnect() usb_gadget_set_state() schedule_work(&gadget->work) Move flush_work() after device_del() to ensure the workqueue is cleaned up.

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_midi: fix MIDI Streaming descriptor lengths While the MIDI jacks are configured correctly, and the MIDIStreaming endpoint descriptors are filled with the correct information, bNumEmbMIDIJack and bLength are set incorrectly in these descriptors. This does not matter when the numbers of in and out ports are equal, but when they differ the host will receive broken descriptors with uninitialized stack memory leaking into the descriptor for whichever value is smaller. The precise meaning of "in" and "out" in the port counts is not clearly defined and can be confusing. But elsewhere the driver consistently uses this to match the USB meaning of IN and OUT viewed from the host, so that "in" ports send data to the host and "out" ports receive data from it.

In the Linux kernel, the following vulnerability has been resolved: block: don't revert iter for -EIOCBQUEUED blkdev_read_iter() has a few odd checks, like gating the position and count adjustment on whether or not the result is bigger-than-or-equal to zero (where bigger than makes more sense), and not checking the return value of blkdev_direct_IO() before doing an iov_iter_revert(). The latter can lead to attempting to revert with a negative value, which when passed to iov_iter_revert() as an unsigned value will lead to throwing a WARN_ON() because unroll is bigger than MAX_RW_COUNT. Be sane and don't revert for -EIOCBQUEUED, like what is done in other spots.

In the Linux kernel, the following vulnerability has been resolved: landlock: Handle weird files A corrupted filesystem (e.g. bcachefs) might return weird files. Instead of throwing a warning and allowing access to such file, treat them as regular files.

In the Linux kernel, the following vulnerability has been resolved: drm/v3d: Stop active perfmon if it is being destroyed If the active performance monitor (`v3d->active_perfmon`) is being destroyed, stop it first. Currently, the active perfmon is not stopped during destruction, leaving the `v3d->active_perfmon` pointer stale. This can lead to undefined behavior and instability. This patch ensures that the active perfmon is stopped before being destroyed, aligning with the behavior introduced in commit 7d1fd3638ee3 ("drm/v3d: Stop the active perfmon before being destroyed").

In the Linux kernel, the following vulnerability has been resolved: tomoyo: don't emit warning in tomoyo_write_control() syzbot is reporting too large allocation warning at tomoyo_write_control(), for one can write a very very long line without new line character. To fix this warning, I use __GFP_NOWARN rather than checking for KMALLOC_MAX_SIZE, for practically a valid line should be always shorter than 32KB where the "too small to fail" memory-allocation rule applies. One might try to write a valid line that is longer than 32KB, but such request will likely fail with -ENOMEM. Therefore, I feel that separately returning -EINVAL when a line is longer than KMALLOC_MAX_SIZE is redundant. There is no need to distinguish over-32KB and over-KMALLOC_MAX_SIZE.

In the Linux kernel, the following vulnerability has been resolved: media: uvcvideo: Fix crash during unbind if gpio unit is in use We used the wrong device for the device managed functions. We used the usb device, when we should be using the interface device. If we unbind the driver from the usb interface, the cleanup functions are never called. In our case, the IRQ is never disabled. If an IRQ is triggered, it will try to access memory sections that are already free, causing an OOPS. We cannot use the function devm_request_threaded_irq here. The devm_* clean functions may be called after the main structure is released by uvc_delete. Luckily this bug has small impact, as it is only affected by devices with gpio units and the user has to unbind the device, a disconnect will not trigger this error.

In the Linux kernel, the following vulnerability has been resolved: ASoC: soc-pcm: don't use soc_pcm_ret() on .prepare callback commit 1f5664351410 ("ASoC: lower "no backend DAIs enabled for ... Port" log severity") ignores -EINVAL error message on common soc_pcm_ret(). It is used from many functions, ignoring -EINVAL is over-kill. The reason why -EINVAL was ignored was it really should only be used upon invalid parameters coming from userspace and in that case we don't want to log an error since we do not want to give userspace a way to do a denial-of-service attack on the syslog / diskspace. So don't use soc_pcm_ret() on .prepare callback is better idea.

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btusb: mediatek: Add locks for usb_driver_claim_interface() The documentation for usb_driver_claim_interface() says that "the device lock" is needed when the function is called from places other than probe(). This appears to be the lock for the USB interface device. The Mediatek btusb code gets called via this path: Workqueue: hci0 hci_power_on [bluetooth] Call trace: usb_driver_claim_interface btusb_mtk_claim_iso_intf btusb_mtk_setup hci_dev_open_sync hci_power_on process_scheduled_works worker_thread kthread With the above call trace the device lock hasn't been claimed. Claim it. Without this fix, we'd sometimes see the error "Failed to claim iso interface". Sometimes we'd even see worse errors, like a NULL pointer dereference (where `intf->dev.driver` was NULL) with a trace like: Call trace: usb_suspend_both usb_runtime_suspend __rpm_callback rpm_suspend pm_runtime_work process_scheduled_works Both errors appear to be fixed with the proper locking.

In the Linux kernel, the following vulnerability has been resolved: bpf: Cancel the running bpf_timer through kworker for PREEMPT_RT During the update procedure, when overwrite element in a pre-allocated htab, the freeing of old_element is protected by the bucket lock. The reason why the bucket lock is necessary is that the old_element has already been stashed in htab->extra_elems after alloc_htab_elem() returns. If freeing the old_element after the bucket lock is unlocked, the stashed element may be reused by concurrent update procedure and the freeing of old_element will run concurrently with the reuse of the old_element. However, the invocation of check_and_free_fields() may acquire a spin-lock which violates the lockdep rule because its caller has already held a raw-spin-lock (bucket lock). The following warning will be reported when such race happens: BUG: scheduling while atomic: test_progs/676/0x00000003 3 locks held by test_progs/676: #0: ffffffff864b0240 (rcu_read_lock_trace){....}-{0:0}, at: bpf_prog_test_run_syscall+0x2c0/0x830 #1: ffff88810e961188 (&htab->lockdep_key){....}-{2:2}, at: htab_map_update_elem+0x306/0x1500 #2: ffff8881f4eac1b8 (&base->softirq_expiry_lock){....}-{2:2}, at: hrtimer_cancel_wait_running+0xe9/0x1b0 Modules linked in: bpf_testmod(O) Preemption disabled at: [<ffffffff817837a3>] htab_map_update_elem+0x293/0x1500 CPU: 0 UID: 0 PID: 676 Comm: test_progs Tainted: G ... 6.12.0+ #11 Tainted: [W]=WARN, [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)... Call Trace: <TASK> dump_stack_lvl+0x57/0x70 dump_stack+0x10/0x20 __schedule_bug+0x120/0x170 __schedule+0x300c/0x4800 schedule_rtlock+0x37/0x60 rtlock_slowlock_locked+0x6d9/0x54c0 rt_spin_lock+0x168/0x230 hrtimer_cancel_wait_running+0xe9/0x1b0 hrtimer_cancel+0x24/0x30 bpf_timer_delete_work+0x1d/0x40 bpf_timer_cancel_and_free+0x5e/0x80 bpf_obj_free_fields+0x262/0x4a0 check_and_free_fields+0x1d0/0x280 htab_map_update_elem+0x7fc/0x1500 bpf_prog_9f90bc20768e0cb9_overwrite_cb+0x3f/0x43 bpf_prog_ea601c4649694dbd_overwrite_timer+0x5d/0x7e bpf_prog_test_run_syscall+0x322/0x830 __sys_bpf+0x135d/0x3ca0 __x64_sys_bpf+0x75/0xb0 x64_sys_call+0x1b5/0xa10 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ... </TASK> It seems feasible to break the reuse and refill of per-cpu extra_elems into two independent parts: reuse the per-cpu extra_elems with bucket lock being held and refill the old_element as per-cpu extra_elems after the bucket lock is unlocked. However, it will make the concurrent overwrite procedures on the same CPU return unexpected -E2BIG error when the map is full. Therefore, the patch fixes the lock problem by breaking the cancelling of bpf_timer into two steps for PREEMPT_RT: 1) use hrtimer_try_to_cancel() and check its return value 2) if the timer is running, use hrtimer_cancel() through a kworker to cancel it again Considering that the current implementation of hrtimer_cancel() will try to acquire a being held softirq_expiry_lock when the current timer is running, these steps above are reasonable. However, it also has downside. When the timer is running, the cancelling of the timer is delayed when releasing the last map uref. The delay is also fixable (e.g., break the cancelling of bpf timer into two parts: one part in locked scope, another one in unlocked scope), it can be revised later if necessary. It is a bit hard to decide the right fix tag. One reason is that the problem depends on PREEMPT_RT which is enabled in v6.12. Considering the softirq_expiry_lock lock exists since v5.4 and bpf_timer is introduced in v5.15, the bpf_timer commit is used in the fixes tag and an extra depends-on tag is added to state the dependency on PREEMPT_RT. Depends-on: v6.12+ with PREEMPT_RT enabled

In the Linux kernel, the following vulnerability has been resolved: drm/i915: Grab intel_display from the encoder to avoid potential oopsies Grab the intel_display from 'encoder' rather than 'state' in the encoder hooks to avoid the massive footgun that is intel_sanitize_encoder(), which passes NULL as the 'state' argument to encoder .disable() and .post_disable(). TODO: figure out how to actually fix intel_sanitize_encoder()...

In the Linux kernel, the following vulnerability has been resolved: team: prevent adding a device which is already a team device lower Prevent adding a device which is already a team device lower, e.g. adding veth0 if vlan1 was already added and veth0 is a lower of vlan1. This is not useful in practice and can lead to recursive locking: $ ip link add veth0 type veth peer name veth1 $ ip link set veth0 up $ ip link set veth1 up $ ip link add link veth0 name veth0.1 type vlan protocol 802.1Q id 1 $ ip link add team0 type team $ ip link set veth0.1 down $ ip link set veth0.1 master team0 team0: Port device veth0.1 added $ ip link set veth0 down $ ip link set veth0 master team0 ============================================ WARNING: possible recursive locking detected 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Not tainted -------------------------------------------- ip/7684 is trying to acquire lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) but task is already holding lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_add_slave (drivers/net/team/team_core.c:1147 drivers/net/team/team_core.c:1977) other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(team->team_lock_key); lock(team->team_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by ip/7684: stack backtrace: CPU: 3 UID: 0 PID: 7684 Comm: ip Not tainted 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:122) print_deadlock_bug.cold (kernel/locking/lockdep.c:3040) __lock_acquire (kernel/locking/lockdep.c:3893 kernel/locking/lockdep.c:5226) ? netlink_broadcast_filtered (net/netlink/af_netlink.c:1548) lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 2)) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? lock_acquire (kernel/locking/lockdep.c:5822) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) __mutex_lock (kernel/locking/mutex.c:587 kernel/locking/mutex.c:735) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? fib_sync_up (net/ipv4/fib_semantics.c:2167) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) __dev_notify_flags (net/core/dev.c:8993) ? __dev_change_flags (net/core/dev.c:8975) dev_change_flags (net/core/dev.c:9027) vlan_device_event (net/8021q/vlan.c:85 net/8021q/vlan.c:470) ? br_device_event (net/bridge/br.c:143) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) dev_open (net/core/dev.c:1519 net/core/dev.c:1505) team_add_slave (drivers/net/team/team_core.c:1219 drivers/net/team/team_core.c:1977) ? __pfx_team_add_slave (drivers/net/team/team_core.c:1972) do_set_master (net/core/rtnetlink.c:2917) do_setlink.isra.0 (net/core/rtnetlink.c:3117)

In the Linux kernel, the following vulnerability has been resolved: OPP: fix dev_pm_opp_find_bw_*() when bandwidth table not initialized If a driver calls dev_pm_opp_find_bw_ceil/floor() the retrieve bandwidth from the OPP table but the bandwidth table was not created because the interconnect properties were missing in the OPP consumer node, the kernel will crash with: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 ... pc : _read_bw+0x8/0x10 lr : _opp_table_find_key+0x9c/0x174 ... Call trace: _read_bw+0x8/0x10 (P) _opp_table_find_key+0x9c/0x174 (L) _find_key+0x98/0x168 dev_pm_opp_find_bw_ceil+0x50/0x88 ... In order to fix the crash, create an assert function to check if the bandwidth table was created before trying to get a bandwidth with _read_bw().

In the Linux kernel, the following vulnerability has been resolved: wifi: rtlwifi: fix memory leaks and invalid access at probe error path Deinitialize at reverse order when probe fails. When init_sw_vars fails, rtl_deinit_core should not be called, specially now that it destroys the rtl_wq workqueue. And call rtl_pci_deinit and deinit_sw_vars, otherwise, memory will be leaked. Remove pci_set_drvdata call as it will already be cleaned up by the core driver code and could lead to memory leaks too. cf. commit 8d450935ae7f ("wireless: rtlwifi: remove unnecessary pci_set_drvdata()") and commit 3d86b93064c7 ("rtlwifi: Fix PCI probe error path orphaned memory").

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: prohibit deactivating all links In the internal API this calls this is a WARN_ON, but that should remain since internally we want to know about bugs that may cause this. Prevent deactivating all links in the debugfs write directly.

In the Linux kernel, the following vulnerability has been resolved: ubifs: skip dumping tnc tree when zroot is null Clearing slab cache will free all znode in memory and make c->zroot.znode = NULL, then dumping tnc tree will access c->zroot.znode which cause null pointer dereference.

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix handling of received connection abort Fix the handling of a connection abort that we've received. Though the abort is at the connection level, it needs propagating to the calls on that connection. Whilst the propagation bit is performed, the calls aren't then woken up to go and process their termination, and as no further input is forthcoming, they just hang. Also add some tracing for the logging of connection aborts.

In the Linux kernel, the following vulnerability has been resolved: remoteproc: core: Fix ida_free call while not allocated In the rproc_alloc() function, on error, put_device(&rproc->dev) is called, leading to the call of the rproc_type_release() function. An error can occurs before ida_alloc is called. In such case in rproc_type_release(), the condition (rproc->index >= 0) is true as rproc->index has been initialized to 0. ida_free() is called reporting a warning: [ 4.181906] WARNING: CPU: 1 PID: 24 at lib/idr.c:525 ida_free+0x100/0x164 [ 4.186378] stm32-display-dsi 5a000000.dsi: Fixed dependency cycle(s) with /soc/dsi@5a000000/panel@0 [ 4.188854] ida_free called for id=0 which is not allocated. [ 4.198256] mipi-dsi 5a000000.dsi.0: Fixed dependency cycle(s) with /soc/dsi@5a000000 [ 4.203556] Modules linked in: panel_orisetech_otm8009a dw_mipi_dsi_stm(+) gpu_sched dw_mipi_dsi stm32_rproc stm32_crc32 stm32_ipcc(+) optee(+) [ 4.224307] CPU: 1 UID: 0 PID: 24 Comm: kworker/u10:0 Not tainted 6.12.0 #442 [ 4.231481] Hardware name: STM32 (Device Tree Support) [ 4.236627] Workqueue: events_unbound deferred_probe_work_func [ 4.242504] Call trace: [ 4.242522] unwind_backtrace from show_stack+0x10/0x14 [ 4.250218] show_stack from dump_stack_lvl+0x50/0x64 [ 4.255274] dump_stack_lvl from __warn+0x80/0x12c [ 4.260134] __warn from warn_slowpath_fmt+0x114/0x188 [ 4.265199] warn_slowpath_fmt from ida_free+0x100/0x164 [ 4.270565] ida_free from rproc_type_release+0x38/0x60 [ 4.275832] rproc_type_release from device_release+0x30/0xa0 [ 4.281601] device_release from kobject_put+0xc4/0x294 [ 4.286762] kobject_put from rproc_alloc.part.0+0x208/0x28c [ 4.292430] rproc_alloc.part.0 from devm_rproc_alloc+0x80/0xc4 [ 4.298393] devm_rproc_alloc from stm32_rproc_probe+0xd0/0x844 [stm32_rproc] [ 4.305575] stm32_rproc_probe [stm32_rproc] from platform_probe+0x5c/0xbc Calling ida_alloc earlier in rproc_alloc ensures that the rproc->index is properly set.

In the Linux kernel, the following vulnerability has been resolved: ipmi: ipmb: Add check devm_kasprintf() returned value devm_kasprintf() can return a NULL pointer on failure but this returned value is not checked.

In the Linux kernel, the following vulnerability has been resolved: driver core: class: Fix wild pointer dereferences in API class_dev_iter_next() There are a potential wild pointer dereferences issue regarding APIs class_dev_iter_(init|next|exit)(), as explained by below typical usage: // All members of @iter are wild pointers. struct class_dev_iter iter; // class_dev_iter_init(@iter, @class, ...) checks parameter @class for // potential class_to_subsys() error, and it returns void type and does // not initialize its output parameter @iter, so caller can not detect // the error and continues to invoke class_dev_iter_next(@iter) even if // @iter still contains wild pointers. class_dev_iter_init(&iter, ...); // Dereference these wild pointers in @iter here once suffer the error. while (dev = class_dev_iter_next(&iter)) { ... }; // Also dereference these wild pointers here. class_dev_iter_exit(&iter); Actually, all callers of these APIs have such usage pattern in kernel tree. Fix by: - Initialize output parameter @iter by memset() in class_dev_iter_init() and give callers prompt by pr_crit() for the error. - Check if @iter is valid in class_dev_iter_next().

In the Linux kernel, the following vulnerability has been resolved: net: xdp: Disallow attaching device-bound programs in generic mode Device-bound programs are used to support RX metadata kfuncs. These kfuncs are driver-specific and rely on the driver context to read the metadata. This means they can't work in generic XDP mode. However, there is no check to disallow such programs from being attached in generic mode, in which case the metadata kfuncs will be called in an invalid context, leading to crashes. Fix this by adding a check to disallow attaching device-bound programs in generic mode.