* patch "vt/fbcon: deinitialize resources in visual_init() after failed memory" added to tty-linus
@ 2019-05-24 15:08 gregkh
0 siblings, 0 replies; only message in thread
From: gregkh @ 2019-05-24 15:08 UTC (permalink / raw)
To: ghalat, b.zolnierkie, gregkh, oleksandr, stable
This is a note to let you know that I've just added the patch titled
vt/fbcon: deinitialize resources in visual_init() after failed memory
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
From a1ad1cc9704f64c169261a76e1aee1cf1ae51832 Mon Sep 17 00:00:00 2001
From: Grzegorz Halat <ghalat@redhat.com>
Date: Fri, 26 Apr 2019 16:59:46 +0200
Subject: 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>
---
drivers/tty/vt/vt.c | 11 +++++++++--
drivers/video/fbdev/core/fbcon.c | 2 +-
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index fdd12f8c3deb..5c0ca1c24b6f 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1056,6 +1056,13 @@ static void visual_init(struct vc_data *vc, int num, int init)
vc->vc_screenbuf_size = vc->vc_rows * vc->vc_size_row;
}
+
+static void visual_deinit(struct vc_data *vc)
+{
+ vc->vc_sw->con_deinit(vc);
+ module_put(vc->vc_sw->owner);
+}
+
int vc_allocate(unsigned int currcons) /* return 0 on success */
{
struct vt_notifier_param param;
@@ -1103,6 +1110,7 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */
return 0;
err_free:
+ visual_deinit(vc);
kfree(vc);
vc_cons[currcons].d = NULL;
return -ENOMEM;
@@ -1331,9 +1339,8 @@ struct vc_data *vc_deallocate(unsigned int currcons)
param.vc = vc = vc_cons[currcons].d;
atomic_notifier_call_chain(&vt_notifier_list, VT_DEALLOCATE, ¶m);
vcs_remove_sysfs(currcons);
- vc->vc_sw->con_deinit(vc);
+ visual_deinit(vc);
put_pid(vc->vt_pid);
- module_put(vc->vc_sw->owner);
vc_uniscr_set(vc, NULL);
kfree(vc->vc_screenbuf);
vc_cons[currcons].d = NULL;
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 786f9aab55df..a9c69ae30878 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -1248,7 +1248,7 @@ static void fbcon_deinit(struct vc_data *vc)
if (free_font)
vc->vc_font.data = NULL;
- if (vc->vc_hi_font_mask)
+ if (vc->vc_hi_font_mask && vc->vc_screenbuf)
set_vc_hi_font(vc, false);
if (!con_is_bound(&fb_con))
--
2.21.0
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