• Grzegorz Halat's avatar
    vt/fbcon: deinitialize resources in visual_init() after failed memory allocation · a1ad1cc9
    Grzegorz Halat authored
    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: default avatarGrzegorz Halat <ghalat@redhat.com>
    Reviewed-by: default avatarOleksandr Natalenko <oleksandr@redhat.com>
    Acked-by: default avatarBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    a1ad1cc9
vt.c 112 KB