From: Grzegorz Halat ghalat@redhat.com
commit a1ad1cc9704f64c169261a76e1aee1cf1ae51832 upstream.
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(-)
--- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -1059,6 +1059,13 @@ static void visual_init(struct vc_data * 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; @@ -1106,6 +1113,7 @@ int vc_allocate(unsigned int currcons) /
return 0; err_free: + visual_deinit(vc); kfree(vc); vc_cons[currcons].d = NULL; return -ENOMEM; @@ -1334,9 +1342,8 @@ struct vc_data *vc_deallocate(unsigned i 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; --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -1237,7 +1237,7 @@ finished: 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))