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linux-stable/drivers/tty
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George Kennedy 3338d0b9ac 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 17:32:51 +01:00
..
hvc hvc/xen: prevent concurrent accesses to the shared ring 2023-03-30 12:49:09 +02:00
ipwireless
serdev
serial serial: qcom-geni: fix enabling deactivated interrupt 2023-05-24 17:32:51 +01:00
vt vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF 2023-05-24 17:32:51 +01:00
amiserial.c tty: Make ->set_termios() old ktermios const 2022-08-30 14:22:35 +02:00
ehv_bytechan.c
goldfish.c
Kconfig
Makefile
mips_ejtag_fdc.c
moxa.c tty: Make ->set_termios() old ktermios const 2022-08-30 14:22:35 +02:00
mxser.c tty: mxser: remove redundant assignment to hwid 2022-09-01 17:59:36 +02:00
n_gsm.c tty: n_gsm: fix sleep-in-atomic-context bug in gsm_control_send 2022-11-03 04:12:09 +01:00
n_hdlc.c tty: n_hdlc: remove HDLC_MAGIC 2022-09-22 16:12:34 +02:00
n_null.c
n_tty.c tty: Make ldisc ->set_termios() old ktermios const 2022-08-30 14:22:34 +02:00
nozomi.c
pty.c tty: Make ->set_termios() old ktermios const 2022-08-30 14:22:35 +02:00
rpmsg_tty.c
synclink_gt.c tty: synclink_gt: remove MGSL_MAGIC 2022-09-22 16:12:34 +02:00
sysrq.c
tty.h tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH 2023-05-11 23:03:01 +09:00
tty_audit.c
tty_baudrate.c tty: Fix comment style in tty_termios_input_baud_rate() 2022-08-30 14:22:34 +02:00
tty_buffer.c tty: Fix lookahead_buf crash with serdev 2022-08-30 14:31:53 +02:00
tty_io.c tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH 2023-05-11 23:03:01 +09:00
tty_ioctl.c tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH 2023-05-11 23:03:01 +09:00
tty_jobctrl.c
tty_ldisc.c
tty_ldsem.c
tty_mutex.c tty: remove TTY_MAGIC 2022-09-22 16:12:34 +02:00
tty_port.c
ttynull.c
vcc.c termios: start unifying non-UAPI parts of asm/termios.h 2022-09-09 10:44:34 +02:00