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18462 CVE
| CVE | Vendors | Products | Updated | CVSS v3.1 |
|---|---|---|---|---|
| CVE-2023-53762 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync Use-after-free can occur in hci_disconnect_all_sync if a connection is deleted by concurrent processing of a controller event. To prevent this the code now tries to iterate over the list backwards to ensure the links are cleanup before its parents, also it no longer relies on a cursor, instead it always uses the last element since hci_abort_conn_sync is guaranteed to call hci_conn_del. UAF crash log: ================================================================== BUG: KASAN: slab-use-after-free in hci_set_powered_sync (net/bluetooth/hci_sync.c:5424) [bluetooth] Read of size 8 at addr ffff888009d9c000 by task kworker/u9:0/124 CPU: 0 PID: 124 Comm: kworker/u9:0 Tainted: G W 6.5.0-rc1+ #10 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Workqueue: hci0 hci_cmd_sync_work [bluetooth] Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0xdd/0x160 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] kasan_report+0xa6/0xe0 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_hci_set_powered_sync+0x10/0x10 [bluetooth] ? __pfx_lock_release+0x10/0x10 ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_cmd_sync_work+0x137/0x220 [bluetooth] process_one_work+0x526/0x9d0 ? __pfx_process_one_work+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? mark_held_locks+0x1a/0x90 worker_thread+0x92/0x630 ? __pfx_worker_thread+0x10/0x10 kthread+0x196/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 </TASK> Allocated by task 1782: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 __kasan_kmalloc+0x8f/0xa0 hci_conn_add+0xa5/0xa80 [bluetooth] hci_bind_cis+0x881/0x9b0 [bluetooth] iso_connect_cis+0x121/0x520 [bluetooth] iso_sock_connect+0x3f6/0x790 [bluetooth] __sys_connect+0x109/0x130 __x64_sys_connect+0x40/0x50 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Freed by task 695: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2b/0x50 __kasan_slab_free+0x10a/0x180 __kmem_cache_free+0x14d/0x2e0 device_release+0x5d/0xf0 kobject_put+0xdf/0x270 hci_disconn_complete_evt+0x274/0x3a0 [bluetooth] hci_event_packet+0x579/0x7e0 [bluetooth] hci_rx_work+0x287/0xaa0 [bluetooth] process_one_work+0x526/0x9d0 worker_thread+0x92/0x630 kthread+0x196/0x1e0 ret_from_fork+0x2c/0x50 ================================================================== | ||||
| CVE-2025-68350 | 1 Linux | 1 Linux Kernel | 2026-04-15 | N/A |
| In the Linux kernel, the following vulnerability has been resolved: exfat: fix divide-by-zero in exfat_allocate_bitmap The variable max_ra_count can be 0 in exfat_allocate_bitmap(), which causes a divide-by-zero error in the subsequent modulo operation (i % max_ra_count), leading to a system crash. When max_ra_count is 0, it means that readahead is not used. This patch load the bitmap without readahead. | ||||
| CVE-2025-68352 | 1 Linux | 1 Linux Kernel | 2026-04-15 | N/A |
| In the Linux kernel, the following vulnerability has been resolved: spi: ch341: fix out-of-bounds memory access in ch341_transfer_one Discovered by Atuin - Automated Vulnerability Discovery Engine. The 'len' variable is calculated as 'min(32, trans->len + 1)', which includes the 1-byte command header. When copying data from 'trans->tx_buf' to 'ch341->tx_buf + 1', using 'len' as the length is incorrect because: 1. It causes an out-of-bounds read from 'trans->tx_buf' (which has size 'trans->len', i.e., 'len - 1' in this context). 2. It can cause an out-of-bounds write to 'ch341->tx_buf' if 'len' is CH341_PACKET_LENGTH (32). Writing 32 bytes to ch341->tx_buf + 1 overflows the buffer. Fix this by copying 'len - 1' bytes. | ||||
| CVE-2025-68353 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: net: vxlan: prevent NULL deref in vxlan_xmit_one Neither sock4 nor sock6 pointers are guaranteed to be non-NULL in vxlan_xmit_one, e.g. if the iface is brought down. This can lead to the following NULL dereference: BUG: kernel NULL pointer dereference, address: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:vxlan_xmit_one+0xbb3/0x1580 Call Trace: vxlan_xmit+0x429/0x610 dev_hard_start_xmit+0x55/0xa0 __dev_queue_xmit+0x6d0/0x7f0 ip_finish_output2+0x24b/0x590 ip_output+0x63/0x110 Mentioned commits changed the code path in vxlan_xmit_one and as a side effect the sock4/6 pointer validity checks in vxlan(6)_get_route were lost. Fix this by adding back checks. Since both commits being fixed were released in the same version (v6.7) and are strongly related, bundle the fixes in a single commit. | ||||
| CVE-2025-68355 | 1 Linux | 1 Linux Kernel | 2026-04-15 | N/A |
| In the Linux kernel, the following vulnerability has been resolved: bpf: Fix exclusive map memory leak When excl_prog_hash is 0 and excl_prog_hash_size is non-zero, the map also needs to be freed. Otherwise, the map memory will not be reclaimed, just like the memory leak problem reported by syzbot [1]. syzbot reported: BUG: memory leak backtrace (crc 7b9fb9b4): map_create+0x322/0x11e0 kernel/bpf/syscall.c:1512 __sys_bpf+0x3556/0x3610 kernel/bpf/syscall.c:6131 | ||||
| CVE-2025-68356 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: gfs2: Prevent recursive memory reclaim Function new_inode() returns a new inode with inode->i_mapping->gfp_mask set to GFP_HIGHUSER_MOVABLE. This value includes the __GFP_FS flag, so allocations in that address space can recurse into filesystem memory reclaim. We don't want that to happen because it can consume a significant amount of stack memory. Worse than that is that it can also deadlock: for example, in several places, gfs2_unstuff_dinode() is called inside filesystem transactions. This calls filemap_grab_folio(), which can allocate a new folio, which can trigger memory reclaim. If memory reclaim recurses into the filesystem and starts another transaction, a deadlock will ensue. To fix these kinds of problems, prevent memory reclaim from recursing into filesystem code by making sure that the gfp_mask of inode address spaces doesn't include __GFP_FS. The "meta" and resource group address spaces were already using GFP_NOFS as their gfp_mask (which doesn't include __GFP_FS). The default value of GFP_HIGHUSER_MOVABLE is less restrictive than GFP_NOFS, though. To avoid being overly limiting, use the default value and only knock off the __GFP_FS flag. I'm not sure if this will actually make a difference, but it also shouldn't hurt. This patch is loosely based on commit ad22c7a043c2 ("xfs: prevent stack overflows from page cache allocation"). Fixes xfstest generic/273. | ||||
| CVE-2025-40136 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: crypto: hisilicon/qm - request reserved interrupt for virtual function The device interrupt vector 3 is an error interrupt for physical function and a reserved interrupt for virtual function. However, the driver has not registered the reserved interrupt for virtual function. When allocating interrupts, the number of interrupts is allocated based on powers of two, which includes this interrupt. When the system enables GICv4 and the virtual function passthrough to the virtual machine, releasing the interrupt in the driver triggers a warning. The WARNING report is: WARNING: CPU: 62 PID: 14889 at arch/arm64/kvm/vgic/vgic-its.c:852 its_free_ite+0x94/0xb4 Therefore, register a reserved interrupt for VF and set the IRQF_NO_AUTOEN flag to avoid that warning. | ||||
| CVE-2025-68375 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: perf/x86: Fix NULL event access and potential PEBS record loss When intel_pmu_drain_pebs_icl() is called to drain PEBS records, the perf_event_overflow() could be called to process the last PEBS record. While perf_event_overflow() could trigger the interrupt throttle and stop all events of the group, like what the below call-chain shows. perf_event_overflow() -> __perf_event_overflow() ->__perf_event_account_interrupt() -> perf_event_throttle_group() -> perf_event_throttle() -> event->pmu->stop() -> x86_pmu_stop() The side effect of stopping the events is that all corresponding event pointers in cpuc->events[] array are cleared to NULL. Assume there are two PEBS events (event a and event b) in a group. When intel_pmu_drain_pebs_icl() calls perf_event_overflow() to process the last PEBS record of PEBS event a, interrupt throttle is triggered and all pointers of event a and event b are cleared to NULL. Then intel_pmu_drain_pebs_icl() tries to process the last PEBS record of event b and encounters NULL pointer access. To avoid this issue, move cpuc->events[] clearing from x86_pmu_stop() to x86_pmu_del(). It's safe since cpuc->active_mask or cpuc->pebs_enabled is always checked before access the event pointer from cpuc->events[]. | ||||
| CVE-2025-26697 | 2 Intel, Linux | 2 Ethernet 700 Series Software, Linux Kernel | 2026-04-15 | 3.3 Low |
| Uncontrolled resource consumption in the Linux kernel-mode driver for some Intel(R) 700 Series Ethernet before version 2.28.5 may allow an authenticated user to potentially enable denial of service. | ||||
| CVE-2023-54156 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: sfc: fix crash when reading stats while NIC is resetting efx_net_stats() (.ndo_get_stats64) can be called during an ethtool selftest, during which time nic_data->mc_stats is NULL as the NIC has been fini'd. In this case do not attempt to fetch the latest stats from the hardware, else we will crash on a NULL dereference: BUG: kernel NULL pointer dereference, address: 0000000000000038 RIP efx_nic_update_stats abridged calltrace: efx_ef10_update_stats_pf efx_net_stats dev_get_stats dev_seq_printf_stats Skipping the read is safe, we will simply give out stale stats. To ensure that the free in efx_ef10_fini_nic() does not race against efx_ef10_update_stats_pf(), which could cause a TOCTTOU bug, take the efx->stats_lock in fini_nic (it is already held across update_stats). | ||||
| CVE-2023-54155 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail() Syzkaller reported the following issue: ======================================= Too BIG xdp->frame_sz = 131072 WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline] WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121 bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103 ... Call Trace: <TASK> bpf_prog_4add87e5301a4105+0x1a/0x1c __bpf_prog_run include/linux/filter.h:600 [inline] bpf_prog_run_xdp include/linux/filter.h:775 [inline] bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721 netif_receive_generic_xdp net/core/dev.c:4807 [inline] do_xdp_generic+0x35c/0x770 net/core/dev.c:4866 tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919 tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043 call_write_iter include/linux/fs.h:1871 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x650/0xe40 fs/read_write.c:584 ksys_write+0x12f/0x250 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd xdp->frame_sz > PAGE_SIZE check was introduced in commit c8741e2bfe87 ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper Dangaard Brouer <jbrouer@redhat.com> noted that after introducing the xdp_init_buff() which all XDP driver use - it's safe to remove this check. The original intend was to catch cases where XDP drivers have not been updated to use xdp.frame_sz, but that is not longer a concern (since xdp_init_buff). Running the initial syzkaller repro it was discovered that the contiguous physical memory allocation is used for both xdp paths in tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also stated by Jesper Dangaard Brouer <jbrouer@redhat.com> that XDP can work on higher order pages, as long as this is contiguous physical memory (e.g. a page). | ||||
| CVE-2025-39978 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: octeontx2-pf: Fix potential use after free in otx2_tc_add_flow() This code calls kfree_rcu(new_node, rcu) and then dereferences "new_node" and then dereferences it on the next line. Two lines later, we take a mutex so I don't think this is an RCU safe region. Re-order it to do the dereferences before queuing up the free. | ||||
| CVE-2023-54115 | 1 Linux | 1 Linux Kernel | 2026-04-15 | N/A |
| In the Linux kernel, the following vulnerability has been resolved: pcmcia: rsrc_nonstatic: Fix memory leak in nonstatic_release_resource_db() When nonstatic_release_resource_db() frees all resources associated with an PCMCIA socket, it forgets to free socket_data too, causing a memory leak observable with kmemleak: unreferenced object 0xc28d1000 (size 64): comm "systemd-udevd", pid 297, jiffies 4294898478 (age 194.484s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 f0 85 0e c3 00 00 00 00 ................ 00 00 00 00 0c 10 8d c2 00 00 00 00 00 00 00 00 ................ backtrace: [<ffda4245>] __kmem_cache_alloc_node+0x2d7/0x4a0 [<7e51f0c8>] kmalloc_trace+0x31/0xa4 [<d52b4ca0>] nonstatic_init+0x24/0x1a4 [pcmcia_rsrc] [<a2f13e08>] pcmcia_register_socket+0x200/0x35c [pcmcia_core] [<a728be1b>] yenta_probe+0x4d8/0xa70 [yenta_socket] [<c48fac39>] pci_device_probe+0x99/0x194 [<84b7c690>] really_probe+0x181/0x45c [<8060fe6e>] __driver_probe_device+0x75/0x1f4 [<b9b76f43>] driver_probe_device+0x28/0xac [<648b766f>] __driver_attach+0xeb/0x1e4 [<6e9659eb>] bus_for_each_dev+0x61/0xb4 [<25a669f3>] driver_attach+0x1e/0x28 [<d8671d6b>] bus_add_driver+0x102/0x20c [<df0d323c>] driver_register+0x5b/0x120 [<942cd8a4>] __pci_register_driver+0x44/0x4c [<e536027e>] __UNIQUE_ID___addressable_cleanup_module188+0x1c/0xfffff000 [iTCO_vendor_support] Fix this by freeing socket_data too. Tested on a Acer Travelmate 4002WLMi by manually binding/unbinding the yenta_cardbus driver (yenta_socket). | ||||
| CVE-2025-40209 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory leak of qgroup_list in btrfs_add_qgroup_relation When btrfs_add_qgroup_relation() is called with invalid qgroup levels (src >= dst), the function returns -EINVAL directly without freeing the preallocated qgroup_list structure passed by the caller. This causes a memory leak because the caller unconditionally sets the pointer to NULL after the call, preventing any cleanup. The issue occurs because the level validation check happens before the mutex is acquired and before any error handling path that would free the prealloc pointer. On this early return, the cleanup code at the 'out' label (which includes kfree(prealloc)) is never reached. In btrfs_ioctl_qgroup_assign(), the code pattern is: prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL); ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst, prealloc); prealloc = NULL; // Always set to NULL regardless of return value ... kfree(prealloc); // This becomes kfree(NULL), does nothing When the level check fails, 'prealloc' is never freed by either the callee or the caller, resulting in a 64-byte memory leak per failed operation. This can be triggered repeatedly by an unprivileged user with access to a writable btrfs mount, potentially exhausting kernel memory. Fix this by freeing prealloc before the early return, ensuring prealloc is always freed on all error paths. | ||||
| CVE-2023-54070 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: igb: clean up in all error paths when enabling SR-IOV After commit 50f303496d92 ("igb: Enable SR-IOV after reinit"), removing the igb module could hang or crash (depending on the machine) when the module has been loaded with the max_vfs parameter set to some value != 0. In case of one test machine with a dual port 82580, this hang occurred: [ 232.480687] igb 0000:41:00.1: removed PHC on enp65s0f1 [ 233.093257] igb 0000:41:00.1: IOV Disabled [ 233.329969] pcieport 0000:40:01.0: AER: Multiple Uncorrected (Non-Fatal) err0 [ 233.340302] igb 0000:41:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fata) [ 233.352248] igb 0000:41:00.0: device [8086:1516] error status/mask=00100000 [ 233.361088] igb 0000:41:00.0: [20] UnsupReq (First) [ 233.368183] igb 0000:41:00.0: AER: TLP Header: 40000001 0000040f cdbfc00c c [ 233.376846] igb 0000:41:00.1: PCIe Bus Error: severity=Uncorrected (Non-Fata) [ 233.388779] igb 0000:41:00.1: device [8086:1516] error status/mask=00100000 [ 233.397629] igb 0000:41:00.1: [20] UnsupReq (First) [ 233.404736] igb 0000:41:00.1: AER: TLP Header: 40000001 0000040f cdbfc00c c [ 233.538214] pci 0000:41:00.1: AER: can't recover (no error_detected callback) [ 233.538401] igb 0000:41:00.0: removed PHC on enp65s0f0 [ 233.546197] pcieport 0000:40:01.0: AER: device recovery failed [ 234.157244] igb 0000:41:00.0: IOV Disabled [ 371.619705] INFO: task irq/35-aerdrv:257 blocked for more than 122 seconds. [ 371.627489] Not tainted 6.4.0-dirty #2 [ 371.632257] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this. [ 371.641000] task:irq/35-aerdrv state:D stack:0 pid:257 ppid:2 f0 [ 371.650330] Call Trace: [ 371.653061] <TASK> [ 371.655407] __schedule+0x20e/0x660 [ 371.659313] schedule+0x5a/0xd0 [ 371.662824] schedule_preempt_disabled+0x11/0x20 [ 371.667983] __mutex_lock.constprop.0+0x372/0x6c0 [ 371.673237] ? __pfx_aer_root_reset+0x10/0x10 [ 371.678105] report_error_detected+0x25/0x1c0 [ 371.682974] ? __pfx_report_normal_detected+0x10/0x10 [ 371.688618] pci_walk_bus+0x72/0x90 [ 371.692519] pcie_do_recovery+0xb2/0x330 [ 371.696899] aer_process_err_devices+0x117/0x170 [ 371.702055] aer_isr+0x1c0/0x1e0 [ 371.705661] ? __set_cpus_allowed_ptr+0x54/0xa0 [ 371.710723] ? __pfx_irq_thread_fn+0x10/0x10 [ 371.715496] irq_thread_fn+0x20/0x60 [ 371.719491] irq_thread+0xe6/0x1b0 [ 371.723291] ? __pfx_irq_thread_dtor+0x10/0x10 [ 371.728255] ? __pfx_irq_thread+0x10/0x10 [ 371.732731] kthread+0xe2/0x110 [ 371.736243] ? __pfx_kthread+0x10/0x10 [ 371.740430] ret_from_fork+0x2c/0x50 [ 371.744428] </TASK> The reproducer was a simple script: #!/bin/sh for i in `seq 1 5`; do modprobe -rv igb modprobe -v igb max_vfs=1 sleep 1 modprobe -rv igb done It turned out that this could only be reproduce on 82580 (quad and dual-port), but not on 82576, i350 and i210. Further debugging showed that igb_enable_sriov()'s call to pci_enable_sriov() is failing, because dev->is_physfn is 0 on 82580. Prior to commit 50f303496d92 ("igb: Enable SR-IOV after reinit"), igb_enable_sriov() jumped into the "err_out" cleanup branch. After this commit it only returned the error code. So the cleanup didn't take place, and the incorrect VF setup in the igb_adapter structure fooled the igb driver into assuming that VFs have been set up where no VF actually existed. Fix this problem by cleaning up again if pci_enable_sriov() fails. | ||||
| CVE-2025-40203 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 7.0 High |
| In the Linux kernel, the following vulnerability has been resolved: listmount: don't call path_put() under namespace semaphore Massage listmount() and make sure we don't call path_put() under the namespace semaphore. If we put the last reference we're fscked. | ||||
| CVE-2025-40117 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: misc: pci_endpoint_test: Fix array underflow in pci_endpoint_test_ioctl() Commit eefb83790a0d ("misc: pci_endpoint_test: Add doorbell test case") added NO_BAR (-1) to the pci_barno enum which, in practical terms, changes the enum from an unsigned int to a signed int. If the user passes a negative number in pci_endpoint_test_ioctl() then it results in an array underflow in pci_endpoint_test_bar(). | ||||
| CVE-2025-40045 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: ASoC: codecs: wcd937x: set the comp soundwire port correctly For some reason we endup with setting soundwire port for HPHL_COMP and HPHR_COMP as zero, this can potentially result in a memory corruption due to accessing and setting -1 th element of port_map array. | ||||
| CVE-2025-40332 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Fix mmap write lock not release If mmap write lock is taken while draining retry fault, mmap write lock is not released because svm_range_restore_pages calls mmap_read_unlock then returns. This causes deadlock and system hangs later because mmap read or write lock cannot be taken. Downgrade mmap write lock to read lock if draining retry fault fix this bug. | ||||
| CVE-2025-40072 | 1 Linux | 1 Linux Kernel | 2026-04-15 | 5.5 Medium |
| In the Linux kernel, the following vulnerability has been resolved: fanotify: Validate the return value of mnt_ns_from_dentry() before dereferencing The function do_fanotify_mark() does not validate if mnt_ns_from_dentry() returns NULL before dereferencing mntns->user_ns. This causes a NULL pointer dereference in do_fanotify_mark() if the path is not a mount namespace object. Fix this by checking mnt_ns_from_dentry()'s return value before dereferencing it. Before the patch $ gcc fanotify_nullptr.c -o fanotify_nullptr $ mkdir A $ ./fanotify_nullptr Fanotify fd: 3 fanotify_mark: Operation not permitted $ unshare -Urm Fanotify fd: 3 Killed int main(void){ int ffd; ffd = fanotify_init(FAN_CLASS_NOTIF | FAN_REPORT_MNT, 0); if(ffd < 0){ perror("fanotify_init"); exit(EXIT_FAILURE); } printf("Fanotify fd: %d\n",ffd); if(fanotify_mark(ffd, FAN_MARK_ADD | FAN_MARK_MNTNS, FAN_MNT_ATTACH, AT_FDCWD, "A") < 0){ perror("fanotify_mark"); exit(EXIT_FAILURE); } return 0; } After the patch $ gcc fanotify_nullptr.c -o fanotify_nullptr $ mkdir A $ ./fanotify_nullptr Fanotify fd: 3 fanotify_mark: Operation not permitted $ unshare -Urm Fanotify fd: 3 fanotify_mark: Invalid argument [ 25.694973] BUG: kernel NULL pointer dereference, address: 0000000000000038 [ 25.695006] #PF: supervisor read access in kernel mode [ 25.695012] #PF: error_code(0x0000) - not-present page [ 25.695017] PGD 109a30067 P4D 109a30067 PUD 142b46067 PMD 0 [ 25.695025] Oops: Oops: 0000 [#1] SMP NOPTI [ 25.695032] CPU: 4 UID: 1000 PID: 1478 Comm: fanotify_nullpt Not tainted 6.17.0-rc4 #1 PREEMPT(lazy) [ 25.695040] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 [ 25.695049] RIP: 0010:do_fanotify_mark+0x817/0x950 [ 25.695066] Code: 04 00 00 e9 45 fd ff ff 48 8b 7c 24 48 4c 89 54 24 18 4c 89 5c 24 10 4c 89 0c 24 e8 b3 11 fc ff 4c 8b 54 24 18 4c 8b 5c 24 10 <48> 8b 78 38 4c 8b 0c 24 49 89 c4 e9 13 fd ff ff 8b 4c 24 28 85 c9 [ 25.695081] RSP: 0018:ffffd31c469e3c08 EFLAGS: 00010203 [ 25.695104] RAX: 0000000000000000 RBX: 0000000001000000 RCX: ffff8eb48aebd220 [ 25.695110] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8eb4835e8180 [ 25.695115] RBP: 0000000000000111 R08: 0000000000000000 R09: 0000000000000000 [ 25.695142] R10: ffff8eb48a7d56c0 R11: ffff8eb482bede00 R12: 00000000004012a7 [ 25.695148] R13: 0000000000000110 R14: 0000000000000001 R15: ffff8eb48a7d56c0 [ 25.695154] FS: 00007f8733bda740(0000) GS:ffff8eb61ce5f000(0000) knlGS:0000000000000000 [ 25.695162] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.695170] CR2: 0000000000000038 CR3: 0000000136994006 CR4: 00000000003706f0 [ 25.695201] Call Trace: [ 25.695209] <TASK> [ 25.695215] __x64_sys_fanotify_mark+0x1f/0x30 [ 25.695222] do_syscall_64+0x82/0x2c0 ... | ||||