linux_dsm_epyc7002/drivers/tty/vt
Grzegorz Halat a1ad1cc970 vt/fbcon: deinitialize resources in visual_init() after failed memory allocation
After memory allocation failure vc_allocate() doesn't clean up data
which has been initialized in visual_init(). In case of fbcon this
leads to divide-by-0 in fbcon_init() on next open of the same tty.

memory allocation in vc_allocate() may fail here:
1097:     vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL);

on next open() fbcon_init() skips vc_font.data initialization:
1088:     if (!p->fontdata) {

division by zero in fbcon_init() happens here:
1149:     new_cols /= vc->vc_font.width;

Additional check is needed in fbcon_deinit() to prevent
usage of uninitialized vc_screenbuf:

1251:        if (vc->vc_hi_font_mask && vc->vc_screenbuf)
1252:                set_vc_hi_font(vc, false);

Crash:

 #6 [ffffc90001eafa60] divide_error at ffffffff81a00be4
    [exception RIP: fbcon_init+463]
    RIP: ffffffff814b860f  RSP: ffffc90001eafb18  RFLAGS: 00010246
...
 #7 [ffffc90001eafb60] visual_init at ffffffff8154c36e
 #8 [ffffc90001eafb80] vc_allocate at ffffffff8154f53c
 #9 [ffffc90001eafbc8] con_install at ffffffff8154f624
...

Signed-off-by: Grzegorz Halat <ghalat@redhat.com>
Reviewed-by: Oleksandr Natalenko <oleksandr@redhat.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:08:18 +02:00
..
.gitignore tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
consolemap.c tty/vt: avoid high order pages allocation on GIO_UNIMAP ioctl 2019-04-16 15:21:34 +02:00
cp437.uni tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
defkeymap.c_shipped tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
defkeymap.map tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
keyboard.c tty: vt: keyboard: Allow Unicode compose base char 2019-04-16 15:21:34 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
selection.c vt: selection: allow functions to be called from inside kernel 2019-04-19 15:09:10 +02:00
vc_screen.c vt: use /dev/vcs (not /dev/vcs0) in comment 2019-03-28 01:28:24 +09:00
vt_ioctl.c Merge branch 'work.tty-ioctl' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-10-24 14:43:41 +01:00
vt.c vt/fbcon: deinitialize resources in visual_init() after failed memory allocation 2019-05-24 17:08:18 +02:00