In the Linux kernel, the following vulnerability has been resolved: fbcon: Set fb_display[i]->mode to NULL when the mode is released Recently, we discovered the following issue through syzkaller: BUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0 Read of size 4 at addr ff11000001b3c69c by task syz.xxx ... Call Trace: <TASK> dump_stack_lvl+0xab/0xe0 print_address_description.constprop.0+0x2c/0x390 print_report+0xb9/0x280 kasan_report+0xb8/0xf0 fb_mode_is_equal+0x285/0x2f0 fbcon_mode_deleted+0x129/0x180 fb_set_var+0xe7f/0x11d0 do_fb_ioctl+0x6a0/0x750 fb_ioctl+0xe0/0x140 __x64_sys_ioctl+0x193/0x210 do_syscall_64+0x5f/0x9c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Based on experimentation and analysis, during framebuffer unregistration, only the memory of fb_info->modelist is freed, without setting the corresponding fb_display[i]->mode to NULL for the freed modes. This leads to UAF issues during subsequent accesses. Here's an example of reproduction steps: 1. With /dev/fb0 already registered in the system, load a kernel module to register a new device /dev/fb1; 2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP); 3. Switch console from fb to VGA (to allow normal rmmod of the ko); 4. Unload the kernel module, at this point fb1's modelist is freed, leaving a wild pointer in fb_display[]; 5. Trigger the bug via system calls through fb0 attempting to delete a mode from fb0. Add a check in do_unregister_framebuffer(): if the mode to be freed exists in fb_display[], set the corresponding mode pointer to NULL.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2025-1350 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none (CVE-2023-53292)

    In the Linux kernel, the following vulnerability has been resolved:

    block: fix race between set_blocksize and read paths (CVE-2025-38073)

    In the Linux kernel, the following vulnerability has been resolved:

    HID: core: Harden s32ton() against conversion to 0 bits (CVE-2025-38556)

    In the Linux kernel, the following vulnerability has been resolved:

    netfilter: nf_tables: reject duplicate device on updates (CVE-2025-38678)

    In the Linux kernel, the following vulnerability has been resolved:

    net/sched: sch_qfq: Fix null-deref in agg_dequeue (CVE-2025-40083)

    In the Linux kernel, the following vulnerability has been resolved:

    ACPI: video: Fix use-after-free in acpi_video_switch_brightness() (CVE-2025-40211)

    In the Linux kernel, the following vulnerability has been resolved:

    af_unix: Initialise scc_index in unix_add_edge(). (CVE-2025-40214)

    In the Linux kernel, the following vulnerability has been resolved:

    vsock: Ignore signal/timeout on connect() if already established (CVE-2025-40248)

    In the Linux kernel, the following vulnerability has been resolved:

    net: openvswitch: remove never-working support for setting nsh fields (CVE-2025-40254)

    In the Linux kernel, the following vulnerability has been resolved:

    mptcp: fix a race in mptcp_pm_del_add_timer() (CVE-2025-40257)

    In the Linux kernel, the following vulnerability has been resolved:

    mptcp: fix race condition in mptcp_schedule_work() (CVE-2025-40258)

    In the Linux kernel, the following vulnerability has been resolved:

    scsi: sg: Do not sleep in atomic context (CVE-2025-40259)

    In the Linux kernel, the following vulnerability has been resolved:

    be2net: pass wrb_params in case of OS2BMC (CVE-2025-40264)

    In the Linux kernel, the following vulnerability has been resolved:

    fs/proc: fix uaf in proc_readdir_de() (CVE-2025-40271)

    In the Linux kernel, the following vulnerability has been resolved:

    mm/secretmem: fix use-after-free race in fault handler (CVE-2025-40272)

    In the Linux kernel, the following vulnerability has been resolved:

    NFSD: free copynotify stateid in nfs4_free_ol_stateid() (CVE-2025-40273)

    In the Linux kernel, the following vulnerability has been resolved:

    drm/vmwgfx: Validate command header size against SVGA_CMD_MAX_DATASIZE (CVE-2025-40277)

    In the Linux kernel, the following vulnerability has been resolved:

    net: sched: act_connmark: initialize struct tc_ife to fix kernel leak (CVE-2025-40279)

    In the Linux kernel, the following vulnerability has been resolved:

    sctp: prevent possible shift-out-of-bounds in sctp_transport_update_rto (CVE-2025-40281)

    In the Linux kernel, the following vulnerability has been resolved:

    virtio-net: fix received length check in big packets (CVE-2025-40292)

    In the Linux kernel, the following vulnerability has been resolved:

    iommufd: Don't overflow during division for dirty tracking (CVE-2025-40293)

    In the Linux kernel, the following vulnerability has been resolved:

    net: bridge: fix use-after-free due to MST port state bypass (CVE-2025-40297)

    In the Linux kernel, the following vulnerability has been resolved:

    fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds (CVE-2025-40304)

    In the Linux kernel, the following vulnerability has been resolved:

    ntfs3: pretend $Extend records as regular files (CVE-2025-40313)

    In the Linux kernel, the following vulnerability has been resolved:

    bpf: Sync pending IRQ work before freeing ring buffer (CVE-2025-40319)

    In the Linux kernel, the following vulnerability has been resolved:

    fbdev: bitblit: bound-check glyph index in bit_putcs* (CVE-2025-40322)

    In the Linux kernel, the following vulnerability has been resolved:

    fbcon: Set fb_display[i]->mode to NULL when the mode is released (CVE-2025-40323)

    In the Linux kernel, the following vulnerability has been resolved:

    NFSD: Fix crash in nfsd4_read_release() (CVE-2025-40324)

    In the Linux kernel, the following vulnerability has been resolved:

    sctp: Prevent TOCTOU out-of-bounds write (CVE-2025-40331)

    In the Linux kernel, the following vulnerability has been resolved:

    futex: Don't leak robust_list pointer on exec race (CVE-2025-40341)

    In the Linux kernel, the following vulnerability has been resolved:

    drm/sysfb: Do not dereference NULL pointer in plane reset (CVE-2025-40360)

    In the Linux kernel, the following vulnerability has been resolved:

    fs: ext4: change GFP_KERNEL to GFP_NOFS to avoid deadlock (CVE-2025-40361)

    In the Linux kernel, the following vulnerability has been resolved:

    net: ipv6: fix field-spanning memcpy warning in AH output (CVE-2025-40363)

    In the Linux kernel, the following vulnerability has been resolved:

    x86/fpu: Ensure XFD state on signal delivery (CVE-2025-68171)

    In the Linux kernel, the following vulnerability has been resolved:

    ftrace: Fix softlockup in ftrace_module_enable (CVE-2025-68173)

    In the Linux kernel, the following vulnerability has been resolved:

    nfs4_setup_readdir(): insufficient locking for ->d_parent->d_inode dereferencing (CVE-2025-68185)

    In the Linux kernel, the following vulnerability has been resolved:

    udp_tunnel: use netdev_warn() instead of netdev_WARN() (CVE-2025-68191)

    In the Linux kernel, the following vulnerability has been resolved:

    bpf: Add bpf_prog_run_data_pointers() (CVE-2025-68200)

    In the Linux kernel, the following vulnerability has been resolved:

    timers: Fix NULL function pointer race in timer_shutdown_sync() (CVE-2025-68214)

    In the Linux kernel, the following vulnerability has been resolved:

    scsi: core: Fix a regression triggered by scsi_host_busy() (CVE-2025-68224)

    In the Linux kernel, the following vulnerability has been resolved:

    mptcp: Fix proto fallback detection with BPF (CVE-2025-68227)

    In the Linux kernel, the following vulnerability has been resolved:

    scsi: target: tcm_loop: Fix segfault in tcm_loop_tpg_address_show() (CVE-2025-68229)

    In the Linux kernel, the following vulnerability has been resolved:

    mm/mempool: fix poisoning order>0 pages with HIGHMEM (CVE-2025-68231)

    In the Linux kernel, the following vulnerability has been resolved:

    ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe (CVE-2025-68241)

    In the Linux kernel, the following vulnerability has been resolved:

    drm/i915: Avoid lock inversion when pinning to GGTT on CHV/BXT+VTD (CVE-2025-68244)

    In the Linux kernel, the following vulnerability has been resolved:

    libceph: replace BUG_ON with bounds check for map->max_osd (CVE-2025-68283)

    In the Linux kernel, the following vulnerability has been resolved:

    libceph: prevent potential out-of-bounds writes in handle_auth_session_key() (CVE-2025-68284)

    In the Linux kernel, the following vulnerability has been resolved:

    libceph: fix potential use-after-free in have_mon_and_osd_map() (CVE-2025-68285)

    In the Linux kernel, the following vulnerability has been resolved:

    usb: dwc3: Fix race condition between concurrent dwc3_remove_requests() call paths (CVE-2025-68287)

    In the Linux kernel, the following vulnerability has been resolved:

    usb: storage: Fix memory leak in USB bulk transport (CVE-2025-68288)

    In the Linux kernel, the following vulnerability has been resolved:

    smb: client: fix memory leak in cifs_construct_tcon() (CVE-2025-68295)

    In the Linux kernel, the following vulnerability has been resolved:

    page_pool: always add GFP_NOWARN for ATOMIC allocations (CVE-2025-68321)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - fbcon: Set fb_display[i]->mode to NULL when the mode is released Recently, we discovered the following     issue through syzkaller: BUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0 Read of size 4 at     addr ff11000001b3c69c by task syz.xxx ... Call Trace: <TASK> dump_stack_lvl+0xab/0xe0     print_address_description.constprop.0+0x2c/0x390 print_report+0xb9/0x280 kasan_report+0xb8/0xf0     fb_mode_is_equal+0x285/0x2f0 fbcon_mode_deleted+0x129/0x180 fb_set_var+0xe7f/0x11d0     do_fb_ioctl+0x6a0/0x750 fb_ioctl+0xe0/0x140 __x64_sys_ioctl+0x193/0x210 do_syscall_64+0x5f/0x9c0     entry_SYSCALL_64_after_hwframe+0x76/0x7e Based on experimentation and analysis, during framebuffer     unregistration, only the memory of fb_info->modelist is freed, without setting the corresponding     fb_display[i]->mode to NULL for the freed modes. This leads to UAF issues during subsequent accesses.
    Here's an example of reproduction steps: 1. With /dev/fb0 already registered in the system, load a kernel     module to register a new device /dev/fb1; 2. Set fb1's mode to the global fb_display[] array (via     FBIOPUT_CON2FBMAP); 3. Switch console from fb to VGA (to allow normal rmmod of the ko); 4. Unload the     kernel module, at this point fb1's modelist is freed, leaving a wild pointer in fb_display[]; 5. Trigger     the bug via system calls through fb0 attempting to delete a mode from fb0. Add a check in     do_unregister_framebuffer(): if the mode to be freed exists in fb_display[], set the corresponding mode     pointer to NULL. (CVE-2025-40323)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
282382	Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2025-1350)	Nessus	Amazon Linux Local Security Checks	high
278075	Photon OS 5.0: Linux PHSA-2025-5.0-0708	Nessus	PhotonOS Local Security Checks	high
277674	Linux Distros Unpatched Vulnerability : CVE-2025-40323	Nessus	Misc.	medium

Detections

Analytics

CVE-2025-40323

medium

Tenable Plugins

high

high

medium