Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: oss: Fix races at processing SysEx messages OSS sequencer handles the SysEx messages split in 6 bytes packets, and ALSA sequencer OSS layer tries to combine those. It stores the data in the internal buffer and this access is racy as of now, which may lead to the out-of-bounds access. As a temporary band-aid fix, introduce a mutex for serializing the process of the SysEx message packets.Show less

Dell Display Manager, versions prior to 2.3.2.20, contain a race condition vulnerability. A local malicious user could potentially exploit this vulnerability during installation, leading to arbitrary folder or file deletion.Show less

A flaw was found in rsync. This vulnerability arises from a race condition during rsync's handling of symbolic links. Rsync's default behavior when encountering symbolic links is to skip them. If an attacker replaced a regular file with a symbolic link at the right time, it was possible to bypass the default behavior and traverse symbolic links. Depending on the privileges of the rsync process, an attacker could leak sensitive information, potentially leading to privilege escalation.Show less

In the Linux kernel, the following vulnerability has been resolved: drm/dp_mst: Fix resetting msg rx state after topology removal If the MST topology is removed during the reception of an MST down reply or MST up request sideband message, the drm_dp_mst_topology_mgr::up_req_recv/down_rep_recv states could be reset from one thread via drm_dp_mst_topology_mgr_set_mst(false), racing with the reading/parsing of the message from another thread via drm_dp_mst_handle_down_rep() or drm_dp_mst_handle_up_req(). The race is possible since the reader/parser doesn't hold any lock while accessing the reception state. This in turn can lead to a memory corruption in the reader/parser as described by commit bd2fccac61b4 ("drm/dp_mst: Fix MST sideband message body length check"). Fix the above by resetting the message reception state if needed before reading/parsing a message. Another solution would be to hold the drm_dp_mst_topology_mgr::lock for the whole duration of the message reception/parsing in drm_dp_mst_handle_down_rep() and drm_dp_mst_handle_up_req(), however this would require a bigger change. Since the fix is also needed for stable, opting for the simpler solution in this patch.Show less

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: oa_tc6: fix tx skb race condition between reference pointers There are two skb pointers to manage tx skb's enqueued from n/w stack. waiting_tx_skb pointer points to the tx skb which needs to be processed and ongoing_tx_skb pointer points to the tx skb which is being processed. SPI thread prepares the tx data chunks from the tx skb pointed by the ongoing_tx_skb pointer. When the tx skb pointed by the ongoing_tx_skb is processed, the tx skb pointed by the waiting_tx_skb is assigned to ongoing_tx_skb and the waiting_tx_skb pointer is assigned with NULL. Whenever there is a new tx skb from n/w stack, it will be assigned to waiting_tx_skb pointer if it is NULL. Enqueuing and processing of a tx skb handled in two different threads. Consider a scenario where the SPI thread processed an ongoing_tx_skb and it moves next tx skb from waiting_tx_skb pointer to ongoing_tx_skb pointer without doing any NULL check. At this time, if the waiting_tx_skb pointer is NULL then ongoing_tx_skb pointer is also assigned with NULL. After that, if a new tx skb is assigned to waiting_tx_skb pointer by the n/w stack and there is a chance to overwrite the tx skb pointer with NULL in the SPI thread. Finally one of the tx skb will be left as unhandled, resulting packet missing and memory leak. - Consider the below scenario where the TXC reported from the previous transfer is 10 and ongoing_tx_skb holds an tx ethernet frame which can be transported in 20 TXCs and waiting_tx_skb is still NULL. tx_credits = 10; /* 21 are filled in the previous transfer */ ongoing_tx_skb = 20; waiting_tx_skb = NULL; /* Still NULL */ - So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true. - After oa_tc6_prepare_spi_tx_buf_for_tx_skbs() ongoing_tx_skb = 10; waiting_tx_skb = NULL; /* Still NULL */ - Perform SPI transfer. - Process SPI rx buffer to get the TXC from footers. - Now let's assume previously filled 21 TXCs are freed so we are good to transport the next remaining 10 tx chunks from ongoing_tx_skb. tx_credits = 21; ongoing_tx_skb = 10; waiting_tx_skb = NULL; - So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true again. - In the oa_tc6_prepare_spi_tx_buf_for_tx_skbs() ongoing_tx_skb = NULL; waiting_tx_skb = NULL; - Now the below bad case might happen, Thread1 (oa_tc6_start_xmit) Thread2 (oa_tc6_spi_thread_handler) --------------------------- ----------------------------------- - if waiting_tx_skb is NULL - if ongoing_tx_skb is NULL - ongoing_tx_skb = waiting_tx_skb - waiting_tx_skb = skb - waiting_tx_skb = NULL ... - ongoing_tx_skb = NULL - if waiting_tx_skb is NULL - waiting_tx_skb = skb To overcome the above issue, protect the moving of tx skb reference from waiting_tx_skb pointer to ongoing_tx_skb pointer and assigning new tx skb to waiting_tx_skb pointer, so that the other thread can't access the waiting_tx_skb pointer until the current thread completes moving the tx skb reference safely.Show less

In the Linux kernel, the following vulnerability has been resolved: s390/cpum_sf: Fix and protect memory allocation of SDBs with mutex Reservation of the PMU hardware is done at first event creation and is protected by a pair of mutex_lock() and mutex_unlock(). After reservation of the PMU hardware the memory required for the PMUs the event is to be installed on is allocated by allocate_buffers() and alloc_sampling_buffer(). This done outside of the mutex protection. Without mutex protection two or more concurrent invocations of perf_event_init() may run in parallel. This can lead to allocation of Sample Data Blocks (SDBs) multiple times for the same PMU. Prevent this and protect memory allocation of SDBs by mutex.Show less

A race condition vulnerability in SimplCommerce at commit 230310c8d7a0408569b292c5a805c459d47a1d8f allows attackers to bypass inventory restrictions by simultaneously submitting purchase requests from multiple accounts for the same product. This can lead to overselling when stock is limited, as the system fails to accurately track inventory under high concurrency, resulting in potential loss and unfulfilled orders.Show less

In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix race between element replace and close() Element replace (with a socket different from the one stored) may race with socket's close() link popping & unlinking. __sock_map_delete() unconditionally unrefs the (wrong) element: // set map[0] = s0 map_update_elem(map, 0, s0) // drop fd of s0 close(s0) sock_map_close() lock_sock(sk) (s0!) sock_map_remove_links(sk) link = sk_psock_link_pop() sock_map_unlink(sk, link) sock_map_delete_from_link // replace map[0] with s1 map_update_elem(map, 0, s1) sock_map_update_elem (s1!) lock_sock(sk) sock_map_update_common psock = sk_psock(sk) spin_lock(&stab->lock) osk = stab->sks[idx] sock_map_add_link(..., &stab->sks[idx]) sock_map_unref(osk, &stab->sks[idx]) psock = sk_psock(osk) sk_psock_put(sk, psock) if (refcount_dec_and_test(&psock)) sk_psock_drop(sk, psock) spin_unlock(&stab->lock) unlock_sock(sk) __sock_map_delete spin_lock(&stab->lock) sk = *psk // s1 replaced s0; sk == s1 if (!sk_test || sk_test == sk) // sk_test (s0) != sk (s1); no branch sk = xchg(psk, NULL) if (sk) sock_map_unref(sk, psk) // unref s1; sks[idx] will dangle psock = sk_psock(sk) sk_psock_put(sk, psock) if (refcount_dec_and_test()) sk_psock_drop(sk, psock) spin_unlock(&stab->lock) release_sock(sk) Then close(map) enqueues bpf_map_free_deferred, which finally calls sock_map_free(). This results in some refcount_t warnings along with a KASAN splat [1]. Fix __sock_map_delete(), do not allow sock_map_unref() on elements that may have been replaced. [1]: BUG: KASAN: slab-use-after-free in sock_map_free+0x10e/0x330 Write of size 4 at addr ffff88811f5b9100 by task kworker/u64:12/1063 CPU: 14 UID: 0 PID: 1063 Comm: kworker/u64:12 Not tainted 6.12.0+ #125 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 Workqueue: events_unbound bpf_map_free_deferred Call Trace: <TASK> dump_stack_lvl+0x68/0x90 print_report+0x174/0x4f6 kasan_report+0xb9/0x190 kasan_check_range+0x10f/0x1e0 sock_map_free+0x10e/0x330 bpf_map_free_deferred+0x173/0x320 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x29e/0x360 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 1202: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x85/0x90 kmem_cache_alloc_noprof+0x131/0x450 sk_prot_alloc+0x5b/0x220 sk_alloc+0x2c/0x870 unix_create1+0x88/0x8a0 unix_create+0xc5/0x180 __sock_create+0x241/0x650 __sys_socketpair+0x1ce/0x420 __x64_sys_socketpair+0x92/0x100 do_syscall_64+0x93/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 46: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x60 __kasan_slab_free+0x4b/0x70 kmem_cache_free+0x1a1/0x590 __sk_destruct+0x388/0x5a0 sk_psock_destroy+0x73e/0xa50 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x29e/0x360 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 The bu ---truncated---Show less

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: Hold module reference while requesting a module User space may unload ip_set.ko while it is itself requesting a set type backend module, leading to a kernel crash. The race condition may be provoked by inserting an mdelay() right after the nfnl_unlock() call.Show less

In the Linux kernel, the following vulnerability has been resolved: net: avoid potential UAF in default_operstate() syzbot reported an UAF in default_operstate() [1] Issue is a race between device and netns dismantles. After calling __rtnl_unlock() from netdev_run_todo(), we can not assume the netns of each device is still alive. Make sure the device is not in NETREG_UNREGISTERED state, and add an ASSERT_RTNL() before the call to __dev_get_by_index(). We might move this ASSERT_RTNL() in __dev_get_by_index() in the future. [1] BUG: KASAN: slab-use-after-free in __dev_get_by_index+0x5d/0x110 net/core/dev.c:852 Read of size 8 at addr ffff888043eba1b0 by task syz.0.0/5339 CPU: 0 UID: 0 PID: 5339 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-10296-gaaf20f870da0 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/report.c:489 kasan_report+0x143/0x180 mm/kasan/report.c:602 __dev_get_by_index+0x5d/0x110 net/core/dev.c:852 default_operstate net/core/link_watch.c:51 [inline] rfc2863_policy+0x224/0x300 net/core/link_watch.c:67 linkwatch_do_dev+0x3e/0x170 net/core/link_watch.c:170 netdev_run_todo+0x461/0x1000 net/core/dev.c:10894 rtnl_unlock net/core/rtnetlink.c:152 [inline] rtnl_net_unlock include/linux/rtnetlink.h:133 [inline] rtnl_dellink+0x760/0x8d0 net/core/rtnetlink.c:3520 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6911 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2541 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:726 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583 ___sys_sendmsg net/socket.c:2637 [inline] __sys_sendmsg+0x269/0x350 net/socket.c:2669 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2a3cb80809 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2a3d9cd058 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f2a3cd45fa0 RCX: 00007f2a3cb80809 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000008 RBP: 00007f2a3cbf393e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2a3cd45fa0 R15: 00007ffd03bc65c8 </TASK> Allocated by task 5339: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4314 kmalloc_noprof include/linux/slab.h:901 [inline] kmalloc_array_noprof include/linux/slab.h:945 [inline] netdev_create_hash net/core/dev.c:11870 [inline] netdev_init+0x10c/0x250 net/core/dev.c:11890 ops_init+0x31e/0x590 net/core/net_namespace.c:138 setup_net+0x287/0x9e0 net/core/net_namespace.c:362 copy_net_ns+0x33f/0x570 net/core/net_namespace.c:500 create_new_namespaces+0x425/0x7b0 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x124/0x180 kernel/nsproxy.c:228 ksys_unshare+0x57d/0xa70 kernel/fork.c:3314 __do_sys_unshare kernel/fork.c:3385 [inline] __se_sys_unshare kernel/fork.c:3383 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3383 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x8 ---truncated---Show less

In the Linux kernel, the following vulnerability has been resolved: media: i2c: tc358743: Fix crash in the probe error path when using polling If an error occurs in the probe() function, we should remove the polling timer that was alarmed earlier, otherwise the timer is called with arguments that are already freed, which results in a crash. ------------[ cut here ]------------ WARNING: CPU: 3 PID: 0 at kernel/time/timer.c:1830 __run_timers+0x244/0x268 Modules linked in: CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.11.0 #226 Hardware name: Diasom DS-RK3568-SOM-EVB (DT) pstate: 804000c9 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __run_timers+0x244/0x268 lr : __run_timers+0x1d4/0x268 sp : ffffff80eff2baf0 x29: ffffff80eff2bb50 x28: 7fffffffffffffff x27: ffffff80eff2bb00 x26: ffffffc080f669c0 x25: ffffff80efef6bf0 x24: ffffff80eff2bb00 x23: 0000000000000000 x22: dead000000000122 x21: 0000000000000000 x20: ffffff80efef6b80 x19: ffffff80041c8bf8 x18: ffffffffffffffff x17: ffffffc06f146000 x16: ffffff80eff27dc0 x15: 000000000000003e x14: 0000000000000000 x13: 00000000000054da x12: 0000000000000000 x11: 00000000000639c0 x10: 000000000000000c x9 : 0000000000000009 x8 : ffffff80eff2cb40 x7 : ffffff80eff2cb40 x6 : ffffff8002bee480 x5 : ffffffc080cb2220 x4 : ffffffc080cb2150 x3 : 00000000000f4240 x2 : 0000000000000102 x1 : ffffff80eff2bb00 x0 : ffffff80041c8bf0 Call trace:  __run_timers+0x244/0x268  timer_expire_remote+0x50/0x68  tmigr_handle_remote+0x388/0x39c  run_timer_softirq+0x38/0x44  handle_softirqs+0x138/0x298  __do_softirq+0x14/0x20  ____do_softirq+0x10/0x1c  call_on_irq_stack+0x24/0x4c  do_softirq_own_stack+0x1c/0x2c  irq_exit_rcu+0x9c/0xcc  el1_interrupt+0x48/0xc0  el1h_64_irq_handler+0x18/0x24  el1h_64_irq+0x7c/0x80  default_idle_call+0x34/0x68  do_idle+0x23c/0x294  cpu_startup_entry+0x38/0x3c  secondary_start_kernel+0x128/0x160  __secondary_switched+0xb8/0xbc ---[ end trace 0000000000000000 ]---Show less

In the Linux kernel, the following vulnerability has been resolved: iommu/arm-smmu: Defer probe of clients after smmu device bound Null pointer dereference occurs due to a race between smmu driver probe and client driver probe, when of_dma_configure() for client is called after the iommu_device_register() for smmu driver probe has executed but before the driver_bound() for smmu driver has been called. Following is how the race occurs: T1:Smmu device probe T2: Client device probe really_probe() arm_smmu_device_probe() iommu_device_register() really_probe() platform_dma_configure() of_dma_configure() of_dma_configure_id() of_iommu_configure() iommu_probe_device() iommu_init_device() arm_smmu_probe_device() arm_smmu_get_by_fwnode() driver_find_device_by_fwnode() driver_find_device() next_device() klist_next() /* null ptr assigned to smmu */ /* null ptr dereference while smmu->streamid_mask */ driver_bound() klist_add_tail() When this null smmu pointer is dereferenced later in arm_smmu_probe_device, the device crashes. Fix this by deferring the probe of the client device until the smmu device has bound to the arm smmu driver. [will: Add comment]Show less

In the Linux kernel, the following vulnerability has been resolved: binder: fix node UAF in binder_add_freeze_work() In binder_add_freeze_work() we iterate over the proc->nodes with the proc->inner_lock held. However, this lock is temporarily dropped in order to acquire the node->lock first (lock nesting order). This can race with binder_node_release() and trigger a use-after-free: ================================================================== BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xe4/0x19c Write of size 4 at addr ffff53c04c29dd04 by task freeze/640 CPU: 5 UID: 0 PID: 640 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #17 Hardware name: linux,dummy-virt (DT) Call trace: _raw_spin_lock+0xe4/0x19c binder_add_freeze_work+0x148/0x478 binder_ioctl+0x1e70/0x25ac __arm64_sys_ioctl+0x124/0x190 Allocated by task 637: __kmalloc_cache_noprof+0x12c/0x27c binder_new_node+0x50/0x700 binder_transaction+0x35ac/0x6f74 binder_thread_write+0xfb8/0x42a0 binder_ioctl+0x18f0/0x25ac __arm64_sys_ioctl+0x124/0x190 Freed by task 637: kfree+0xf0/0x330 binder_thread_read+0x1e88/0x3a68 binder_ioctl+0x16d8/0x25ac __arm64_sys_ioctl+0x124/0x190 ================================================================== Fix the race by taking a temporary reference on the node before releasing the proc->inner lock. This ensures the node remains alive while in use.Show less

In the Linux kernel, the following vulnerability has been resolved: drm/xe/guc_submit: fix race around suspend_pending Currently in some testcases we can trigger: xe 0000:03:00.0: [drm] Assertion `exec_queue_destroyed(q)` failed! .... WARNING: CPU: 18 PID: 2640 at drivers/gpu/drm/xe/xe_guc_submit.c:1826 xe_guc_sched_done_handler+0xa54/0xef0 [xe] xe 0000:03:00.0: [drm] *ERROR* GT1: DEREGISTER_DONE: Unexpected engine state 0x00a1, guc_id=57 Looking at a snippet of corresponding ftrace for this GuC id we can see: 162.673311: xe_sched_msg_add: dev=0000:03:00.0, gt=1 guc_id=57, opcode=3 162.673317: xe_sched_msg_recv: dev=0000:03:00.0, gt=1 guc_id=57, opcode=3 162.673319: xe_exec_queue_scheduling_disable: dev=0000:03:00.0, 1:0x2, gt=1, width=1, guc_id=57, guc_state=0x29, flags=0x0 162.674089: xe_exec_queue_kill: dev=0000:03:00.0, 1:0x2, gt=1, width=1, guc_id=57, guc_state=0x29, flags=0x0 162.674108: xe_exec_queue_close: dev=0000:03:00.0, 1:0x2, gt=1, width=1, guc_id=57, guc_state=0xa9, flags=0x0 162.674488: xe_exec_queue_scheduling_done: dev=0000:03:00.0, 1:0x2, gt=1, width=1, guc_id=57, guc_state=0xa9, flags=0x0 162.678452: xe_exec_queue_deregister: dev=0000:03:00.0, 1:0x2, gt=1, width=1, guc_id=57, guc_state=0xa1, flags=0x0 It looks like we try to suspend the queue (opcode=3), setting suspend_pending and triggering a disable_scheduling. The user then closes the queue. However the close will also forcefully signal the suspend fence after killing the queue, later when the G2H response for disable_scheduling comes back we have now cleared suspend_pending when signalling the suspend fence, so the disable_scheduling now incorrectly tries to also deregister the queue. This leads to warnings since the queue has yet to even be marked for destruction. We also seem to trigger errors later with trying to double unregister the same queue. To fix this tweak the ordering when handling the response to ensure we don't race with a disable_scheduling that didn't actually intend to perform an unregister. The destruction path should now also correctly wait for any pending_disable before marking as destroyed. (cherry picked from commit f161809b362f027b6d72bd998e47f8f0bad60a2e)Show less

In the Linux kernel, the following vulnerability has been resolved: accel/ivpu: Prevent recovery invocation during probe and resume Refactor IPC send and receive functions to allow correct handling of operations that should not trigger a recovery process. Expose ivpu_send_receive_internal(), which is now utilized by the D0i3 entry, DCT initialization, and HWS initialization functions. These functions have been modified to return error codes gracefully, rather than initiating recovery. The updated functions are invoked within ivpu_probe() and ivpu_resume(), ensuring that any errors encountered during these stages result in a proper teardown or shutdown sequence. The previous approach of triggering recovery within these functions could lead to a race condition, potentially causing undefined behavior and kernel crashes due to null pointer dereferences.Show less

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in SMB request handling A race condition exists between SMB request handling in `ksmbd_conn_handler_loop()` and the freeing of `ksmbd_conn` in the workqueue handler `handle_ksmbd_work()`. This leads to a UAF. - KASAN: slab-use-after-free Read in handle_ksmbd_work - KASAN: slab-use-after-free in rtlock_slowlock_locked This race condition arises as follows: - `ksmbd_conn_handler_loop()` waits for `conn->r_count` to reach zero: `wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);` - Meanwhile, `handle_ksmbd_work()` decrements `conn->r_count` using `atomic_dec_return(&conn->r_count)`, and if it reaches zero, calls `ksmbd_conn_free()`, which frees `conn`. - However, after `handle_ksmbd_work()` decrements `conn->r_count`, it may still access `conn->r_count_q` in the following line: `waitqueue_active(&conn->r_count_q)` or `wake_up(&conn->r_count_q)` This results in a UAF, as `conn` has already been freed. The discovery of this UAF can be referenced in the following PR for syzkaller's support for SMB requests.Show less