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authorGrzegorz Halat <ghalat@redhat.com>2019-04-26 17:59:46 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-24 18:08:18 +0300
commita1ad1cc9704f64c169261a76e1aee1cf1ae51832 (patch)
tree68930207b4e0231d10ae0fbfe8b3d512f8ae1ac2 /drivers/tty
parent5d24f455c182d5116dd5db8e1dc501115ecc9c2c (diff)
downloadlinux-a1ad1cc9704f64c169261a76e1aee1cf1ae51832.tar.xz
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>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/vt/vt.c11
1 files changed, 9 insertions, 2 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, &param);
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;