{"id":"CVE-2023-53747","summary":"vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF\n\nAfter a call to console_unlock() in vcs_write() the vc_data struct can be\nfreed by vc_port_destruct(). Because of that, the struct vc_data pointer\nmust be reloaded in the while loop in vcs_write() after console_lock() to\navoid a UAF when vcs_size() is called.\n\nSyzkaller reported a UAF in vcs_size().\n\nBUG: KASAN: slab-use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)\nRead of size 4 at addr ffff8880beab89a8 by task repro_vcs_size/4119\n\nCall Trace:\n \u003cTASK\u003e\n__asan_report_load4_noabort (mm/kasan/report_generic.c:380)\nvcs_size (drivers/tty/vt/vc_screen.c:215)\nvcs_write (drivers/tty/vt/vc_screen.c:664)\nvfs_write (fs/read_write.c:582 fs/read_write.c:564)\n...\n \u003cTASK\u003e\n\nAllocated by task 1213:\nkmalloc_trace (mm/slab_common.c:1064)\nvc_allocate (./include/linux/slab.h:559 ./include/linux/slab.h:680\n    drivers/tty/vt/vt.c:1078 drivers/tty/vt/vt.c:1058)\ncon_install (drivers/tty/vt/vt.c:3334)\ntty_init_dev (drivers/tty/tty_io.c:1303 drivers/tty/tty_io.c:1415\n    drivers/tty/tty_io.c:1392)\ntty_open (drivers/tty/tty_io.c:2082 drivers/tty/tty_io.c:2128)\nchrdev_open (fs/char_dev.c:415)\ndo_dentry_open (fs/open.c:921)\nvfs_open (fs/open.c:1052)\n...\n\nFreed by task 4116:\nkfree (mm/slab_common.c:1016)\nvc_port_destruct (drivers/tty/vt/vt.c:1044)\ntty_port_destructor (drivers/tty/tty_port.c:296)\ntty_port_put (drivers/tty/tty_port.c:312)\nvt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))\nvt_ioctl (drivers/tty/vt/vt_ioctl.c:903)\ntty_ioctl (drivers/tty/tty_io.c:2778)\n...\n\nThe buggy address belongs to the object at ffff8880beab8800\n which belongs to the cache kmalloc-1k of size 1024\nThe buggy address is located 424 bytes inside of\n freed 1024-byte region [ffff8880beab8800, ffff8880beab8c00)\n\nThe buggy address belongs to the physical page:\npage:00000000afc77580 refcount:1 mapcount:0 mapping:0000000000000000\n    index:0x0 pfn:0xbeab8\nhead:00000000afc77580 order:3 entire_mapcount:0 nr_pages_mapped:0\n    pincount:0\nflags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)\npage_type: 0xffffffff()\nraw: 000fffffc0010200 ffff888100042dc0 ffffea000426de00 dead000000000002\nraw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n ffff8880beab8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8880beab8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\u003effff8880beab8980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                                  ^\n ffff8880beab8a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8880beab8a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n==================================================================\nDisabling lock debugging due to kernel taint","modified":"2026-04-02T09:45:03.918632Z","published":"2025-12-08T01:19:06.255Z","related":["SUSE-SU-2026:0263-1","SUSE-SU-2026:0317-1","SUSE-SU-2026:0411-1","SUSE-SU-2026:0473-1","SUSE-SU-2026:0617-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53747.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0deff678157333d775af190f84696336cdcccd6d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/11dddfbb7a4e62489b01074d6c04d9d1b42e4047"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1de42e7653d6714a7507ba6696151a1fa028c69f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3338d0b9acde770ee588eead5cac32c25e7048fc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357"},{"type":"WEB","url":"https://git.kernel.org/stable/c/934de9a9b659785fed3e820bc0c813a460c71fea"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a4e3c4c65ae8510e01352c9a4347e05c035b2ce2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e3d1adcad5b73c7ed0c7edb35ab68abcaa45cf67"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53747.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53747"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff"},{"fixed":"934de9a9b659785fed3e820bc0c813a460c71fea"},{"fixed":"0deff678157333d775af190f84696336cdcccd6d"},{"fixed":"a4e3c4c65ae8510e01352c9a4347e05c035b2ce2"},{"fixed":"11dddfbb7a4e62489b01074d6c04d9d1b42e4047"},{"fixed":"e3d1adcad5b73c7ed0c7edb35ab68abcaa45cf67"},{"fixed":"3338d0b9acde770ee588eead5cac32c25e7048fc"},{"fixed":"1de42e7653d6714a7507ba6696151a1fa028c69f"},{"fixed":"8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53747.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.38"},{"fixed":"4.14.327"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.15.0"},{"fixed":"4.19.284"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"5.4.244"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.181"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.113"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.30"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.3.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53747.json"}}],"schema_version":"1.7.5"}