CVE-2025-40323— fbcon: Set fb_display[i]->mode to NULL when the mode is released
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I. Basic Information for CVE-2025-40323
Vulnerability Information
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Vulnerability Title
fbcon: Set fb_display[i]->mode to NULL when the mode is released
Source: NVD (National Vulnerability Database)
Vulnerability Description
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.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未设置fb_display[i]->mode为NULL，可能导致释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2025-40323
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Same Patch Batch · Linux · 2025-12-08 · 82 CVEs total
| CVE-2022-50630 | mm: hugetlb: fix UAF in hugetlb_handle_userfault | |
| CVE-2023-53752 | net: deal with integer overflows in kmalloc_reserve() | |
| CVE-2022-50627 | wifi: ath11k: fix monitor mode bringup crash | |
| CVE-2022-50628 | drm/gud: Fix UBSAN warning | |
| CVE-2022-50626 | media: dvb-usb: fix memory leak in dvb_usb_adapter_init() | |
| CVE-2022-50623 | fpga: prevent integer overflow in dfl_feature_ioctl_set_irq() | |
| CVE-2022-50622 | ext4: fix potential memory leak in ext4_fc_record_modified_inode() | |
| CVE-2022-50621 | dm: verity-loadpin: Only trust verity targets with enforcement | |
| CVE-2022-50620 | f2fs: fix to invalidate dcc->f2fs_issue_discard in error path | |
| CVE-2022-50624 | net: netsec: fix error handling in netsec_register_mdio() | |
| CVE-2022-50629 | wifi: rsi: Fix memory leak in rsi_coex_attach() | |
| CVE-2023-53742 | kcsan: Avoid READ_ONCE() in read_instrumented_memory() | |
| CVE-2023-53743 | PCI: Free released resource after coalescing | |
| CVE-2023-53744 | soc: ti: pm33xx: Fix refcount leak in am33xx_pm_probe | |
| CVE-2023-53745 | um: vector: Fix memory leak in vector_config | |
| CVE-2023-53746 | s390/vfio-ap: fix memory leak in vfio_ap device driver | |
| CVE-2023-53747 | vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF | |
| CVE-2023-53748 | media: mediatek: vcodec: Fix potential array out-of-bounds in decoder queue_setup | |
| CVE-2023-53750 | pinctrl: freescale: Fix a memory out of bounds when num_configs is 1 | |
| CVE-2023-53751 | cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname |
Showing top 20 of 82 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
- CVE-2026-43500
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scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
Same vendor: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
V. Comments for CVE-2025-40323
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