fbcon: Use kzalloc() in fbcon_prepare_logo()
A kernel built with syzbot's config file reported that scr_memcpyw(q, save, array3_size(logo_lines, new_cols, 2)) causes uninitialized "save" to be copied. ---------- [drm] Initialized vgem 1.0.0 20120112 for vgem on minor 0 [drm] Initialized vkms 1.0.0 20180514 for vkms on minor 1 Console: switching to colour frame buffer device 128x48 ===================================================== BUG: KMSAN: uninit-value in do_update_region+0x4b8/0xba0 do_update_region+0x4b8/0xba0 update_region+0x40d/0x840 fbcon_switch+0x3364/0x35e0 redraw_screen+0xae3/0x18a0 do_bind_con_driver+0x1cb3/0x1df0 do_take_over_console+0x11cb/0x13f0 fbcon_fb_registered+0xacc/0xfd0 register_framebuffer+0x1179/0x1320 __drm_fb_helper_initial_config_and_unlock+0x23ad/0x2b40 drm_fbdev_client_hotplug+0xbea/0xda0 drm_fbdev_generic_setup+0x65e/0x9d0 vkms_init+0x9f3/0xc76 (...snipped...) Uninit was stored to memory at: fbcon_prepare_logo+0x143b/0x1940 fbcon_init+0x2c1b/0x31c0 visual_init+0x3e7/0x820 do_bind_con_driver+0x14a4/0x1df0 do_take_over_console+0x11cb/0x13f0 fbcon_fb_registered+0xacc/0xfd0 register_framebuffer+0x1179/0x1320 __drm_fb_helper_initial_config_and_unlock+0x23ad/0x2b40 drm_fbdev_client_hotplug+0xbea/0xda0 drm_fbdev_generic_setup+0x65e/0x9d0 vkms_init+0x9f3/0xc76 (...snipped...) Uninit was created at: __kmem_cache_alloc_node+0xb69/0x1020 __kmalloc+0x379/0x680 fbcon_prepare_logo+0x704/0x1940 fbcon_init+0x2c1b/0x31c0 visual_init+0x3e7/0x820 do_bind_con_driver+0x14a4/0x1df0 do_take_over_console+0x11cb/0x13f0 fbcon_fb_registered+0xacc/0xfd0 register_framebuffer+0x1179/0x1320 __drm_fb_helper_initial_config_and_unlock+0x23ad/0x2b40 drm_fbdev_client_hotplug+0xbea/0xda0 drm_fbdev_generic_setup+0x65e/0x9d0 vkms_init+0x9f3/0xc76 (...snipped...) CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc4-00356-g8f2975c2bb4c #924 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 ---------- Signed-off-by:Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: