In the Linux kernel, the following vulnerability has been resolved:
vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF
After a call to console_unlock() in vcs_read() the vc_data struct can be freed by vc_deallocate(). Because of that, the struct vc_data pointer load must be done at the top of while loop in vcs_read() to avoid a UAF when vcs_size() is called.
Syzkaller reported a UAF in vcs_size().
BUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215) Read of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537
CPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1 Hardware name: Red Hat KVM, BIOS 1.15.0-2.module Call Trace: <TASK> __asan_report_load4_noabort (mm/kasan/report_generic.c:350) vcs_size (drivers/tty/vt/vc_screen.c:215) vcs_read (drivers/tty/vt/vc_screen.c:415) vfs_read (fs/read_write.c:468 fs/read_write.c:450) ... </TASK>
Allocated by task 1191: ... kmalloc_trace (mm/slab_common.c:1069) vc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720 drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108) con_install (drivers/tty/vt/vt.c:3383) tty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413 drivers/tty/tty_io.c:1390) tty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126) chrdev_open (fs/char_dev.c:415) do_dentry_open (fs/open.c:883) vfs_open (fs/open.c:1014) ...
Freed by task 1548: ... kfree (mm/slab_common.c:1021) vc_port_destruct (drivers/tty/vt/vt.c:1094) 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:2776) ...
The buggy address belongs to the object at ffff888113747800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 424 bytes inside of 1024-byte region [ffff888113747800, ffff888113747c00)
The buggy address belongs to the physical page: page:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113740 head:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0 anon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Disabling lock debugging due to kernel taint
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-livepatch-4.14.330-250.540Upgrade python-perf-debuginfoUpgrade python-perfUpgrade perf-debuginfoUpgrade kernel-tools-develUpgrade perfUpgrade kernel-headersUpgrade kernel-livepatch-5.10.173-154.642Upgrade kernel-debuginfo-common-aarch64Upgrade bpftool-debuginfoUpgrade kernel-livepatch-5.15.93-55.139Upgrade bpftoolUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfoUpgrade kernelUpgrade kernel-develUpgrade kernel-tools-debuginfoUpgrade kernel-tools | Apr 25, 2025 | Mar 27, 2025 |
| Amazon_linux | — | Upgrade kernel | Apr 30, 2025 | Mar 27, 2025 |
| Amazon_linux_2023 | — | Upgrade kernel-develUpgrade kernel-headersUpgrade kernel-debuginfo-common-aarch64Upgrade python3-perfUpgrade kernel-livepatch-6.1.12-17.42Upgrade perfUpgrade perf-debuginfoUpgrade kernel-tools-develUpgrade kernel-libbpf-develUpgrade bpftool-debuginfoUpgrade kernelUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-libbpfUpgrade python3-perf-debuginfoUpgrade kernel-toolsUpgrade kernel-libbpf-staticUpgrade kernel-tools-debuginfoUpgrade kernel-debuginfoUpgrade bpftool | Apr 30, 2025 | Mar 27, 2025 |
| Debian | — | Upgrade linux | Mar 31, 2025 | Mar 27, 2025 |
| Huawei Euleros 2_0_sp10 | — | Upgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade kernelUpgrade python3-perfUpgrade kernel-tools | Jul 11, 2025 | Mar 27, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade python3-perfUpgrade kernelUpgrade kernel-tools-libs | Jul 1, 2025 | Mar 27, 2025 |
| Redhat_linux | — | Upgrade kernelNo solution existsUpgrade kernel-rt | Jul 9, 2025 | Mar 27, 2025 |
| Ubuntu | — | Upgrade linux-azure-fdeUpgrade linux-kvmUpgrade linux-azure-5.15Upgrade linux-nvidiaUpgrade linux-gcp-fipsUpgrade linux-gcp-5.15Upgrade linux-gcpUpgrade linux-xilinx-zynqmpUpgrade linux-intel-iot-realtimeUpgrade linux-ibmUpgrade linux-riscv-5.15Upgrade linux-realtimeUpgrade linux-oracleUpgrade linux-gkeUpgrade linux-intel-iotgUpgrade linux-oracle-5.4Upgrade linux-fipsUpgrade linux-lowlatency-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-raspi-5.4Upgrade linux-bluefieldUpgrade linux-gkeopUpgrade linux-aws-5.4Upgrade linux-oracle-5.15Upgrade linux-lts-xenialUpgrade linuxUpgrade linux-azure-fipsUpgrade linux-azure-5.4Upgrade linux-hweUpgrade linux-aws-hweUpgrade linux-aws-5.15Upgrade linux-nvidia-tegra-5.15Upgrade linux-gcp-5.4Upgrade linux-lowlatencyUpgrade linux-iotUpgrade linux-azure-4.15Upgrade linux-gcp-4.15Upgrade linux-hwe-5.4Upgrade linux-ibm-5.4Upgrade linux-aws-fipsUpgrade linux-azureUpgrade linux-raspiUpgrade linux-hwe-5.15Upgrade linux-aws | Apr 1, 2025 | Mar 27, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Mar 27, 2025 |
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