George Kennedy e3d1adcad5 vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF ... commit 8fb9ea65c9 upstream. 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 Fixes: ac751efa6a ("console: rename acquire/release_console_sem() to console_lock/unlock()") Cc: stable <stable@kernel.org> Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: George Kennedy <george.kennedy@oracle.com> Reviewed-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://lore.kernel.org/r/1683889728-10411-1-git-send-email-george.kennedy@oracle.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2023-05-24 17:36:54 +01:00
..
.gitignore	.gitignore: prefix local generated files with a slash	2021-05-02 00:43:35 +09:00
Makefile	…
conmakehash.c	…
consolemap.c	vt/consolemap: do font sum unsigned	2021-01-07 16:17:31 +01:00
cp437.uni	…
defkeymap.c_shipped	vt: keyboard, defkeymap.c_shipped, approach the unicode table	2021-01-07 16:17:31 +01:00
defkeymap.map	…
keyboard.c	tty: drivers/tty/, stop using tty_schedule_flip()	2022-07-29 17:25:31 +02:00
selection.c	tty: vt: selection: Correct misspelled function sel_loadlut()	2021-05-20 17:05:33 +02:00
vc_screen.c	vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF	2023-05-24 17:36:54 +01:00
vt.c	vt: Clear selection before changing the font	2022-09-08 12:28:03 +02:00
vt_ioctl.c	vt_ioctl: add array_index_nospec to VT_ACTIVATE	2022-02-16 12:56:33 +01:00