In the Linux kernel, the following vulnerability has been resolved:
vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF
After a call to console_unlock() in vcs_write() the vc_data struct can be freed by vc_port_destruct(). Because of that, the struct vc_data pointer must be reloaded in the while loop in vcs_write() after console_lock() to avoid a UAF when vcs_size() is called.
Syzkaller reported a UAF in vcs_size().
BUG: KASAN: slab-use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215) Read of size 4 at addr ffff8880beab89a8 by task repro_vcs_size/4119
Call Trace: <TASK> __asan_report_load4_noabort (mm/kasan/report_generic.c:380) vcs_size (drivers/tty/vt/vc_screen.c:215) vcs_write (drivers/tty/vt/vc_screen.c:664) vfs_write (fs/read_write.c:582 fs/read_write.c:564) ... <TASK>
Allocated by task 1213: kmalloc_trace (mm/slab_common.c:1064) vc_allocate (./include/linux/slab.h:559 ./include/linux/slab.h:680 drivers/tty/vt/vt.c:1078 drivers/tty/vt/vt.c:1058) con_install (drivers/tty/vt/vt.c:3334) tty_init_dev (drivers/tty/tty_io.c:1303 drivers/tty/tty_io.c:1415 drivers/tty/tty_io.c:1392) tty_open (drivers/tty/tty_io.c:2082 drivers/tty/tty_io.c:2128) chrdev_open (fs/char_dev.c:415) do_dentry_open (fs/open.c:921) vfs_open (fs/open.c:1052) ...
Freed by task 4116: kfree (mm/slab_common.c:1016) vc_port_destruct (drivers/tty/vt/vt.c:1044) tty_port_destructor (drivers/tty/tty_port.c:296) tty_port_put (drivers/tty/tty_port.c:312) vt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2)) vt_ioctl (drivers/tty/vt/vt_ioctl.c:903) tty_ioctl (drivers/tty/tty_io.c:2778) ...
The buggy address belongs to the object at ffff8880beab8800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 424 bytes inside of freed 1024-byte region [ffff8880beab8800, ffff8880beab8c00)
The buggy address belongs to the physical page: page:00000000afc77580 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xbeab8 head:00000000afc77580 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 000fffffc0010200 ffff888100042dc0 ffffea000426de00 dead000000000002 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880beab8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880beab8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880beab8980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880beab8a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880beab8a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Disabling lock debugging due to kernel taint
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade perf-debuginfoUpgrade kernel-headersUpgrade kernel-livepatch-5.15.117-72.142Upgrade kernelUpgrade python-perfUpgrade kernel-toolsUpgrade kernel-tools-develUpgrade python-perf-debuginfoUpgrade perfUpgrade bpftool-debuginfoUpgrade kernel-develUpgrade kernel-tools-debuginfoUpgrade bpftoolUpgrade kernel-livepatch-4.14.327-246.539Upgrade kernel-debuginfo-common-aarch64Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfoUpgrade kernel-livepatch-5.10.184-174.730 | May 20, 2026 | May 20, 2026 |
| Amazon_linux_2023 | — | Upgrade kernel-libbpf-develUpgrade kernel-libbpf-staticUpgrade kernelUpgrade bpftoolUpgrade kernel-develUpgrade kernel-toolsUpgrade python3-perf-debuginfoUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-livepatch-6.1.34-56.100Upgrade kernel-headersUpgrade kernel-tools-develUpgrade python3-perfUpgrade bpftool-debuginfoUpgrade kernel-debuginfoUpgrade kernel-libbpfUpgrade kernel-tools-debuginfoUpgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfo | Jan 12, 2026 | Dec 8, 2025 |
| Debian | — | Upgrade linux | Dec 9, 2025 | Dec 9, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade python3-perfUpgrade bpftoolUpgrade kernelUpgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade kernel-tools | Mar 10, 2026 | Mar 10, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 8, 2025 |
| Ubuntu | — | Upgrade linux-azure-5.15Upgrade linux-gkeopUpgrade linux-hwe-5.4Upgrade linux-gcp-fipsUpgrade linux-azureUpgrade linux-iotUpgrade linux-gcp-5.15Upgrade linux-azure-fipsUpgrade linux-ibmUpgrade linux-realtimeUpgrade linux-hwe-5.15Upgrade linux-azure-5.4Upgrade linux-kvmUpgrade linux-gcp-5.4Upgrade linux-oracleUpgrade linux-aws-fipsUpgrade linux-xilinx-zynqmpUpgrade linux-nvidiaUpgrade linux-intel-iotg-5.15Upgrade linux-nvidia-tegra-igxUpgrade linux-aws-5.4Upgrade linux-oracle-5.4Upgrade linux-intel-iot-realtimeUpgrade linux-aws-5.15Upgrade linux-awsUpgrade linux-lowlatencyUpgrade linux-ibm-5.4Upgrade linux-riscv-5.15Upgrade linux-ibm-5.15Upgrade linux-intel-iotgUpgrade linux-lowlatency-hwe-5.15Upgrade linux-oracle-5.15Upgrade linux-gkeUpgrade linux-nvidia-tegraUpgrade linux-fipsUpgrade linux-raspi-5.4Upgrade linux-bluefieldUpgrade linuxUpgrade linux-nvidia-tegra-5.15Upgrade linux-gcpUpgrade linux-raspi | Dec 10, 2025 | Dec 8, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 8, 2025 |
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