From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
[ Upstream commit a6a00d7e8ffd78d1cdb7a43f1278f081038c638f ]
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: Daniel Vetter daniel.vetter@ffwll.ch Link: https://patchwork.freedesktop.org/patch/msgid/cad03d25-0ea0-32c4-8173-fd1895... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/core/fbcon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 098b62f7b701..c0143d38df83 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -577,7 +577,7 @@ static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info, if (scr_readw(r) != vc->vc_video_erase_char) break; if (r != q && new_rows >= rows + logo_lines) { - save = kmalloc(array3_size(logo_lines, new_cols, 2), + save = kzalloc(array3_size(logo_lines, new_cols, 2), GFP_KERNEL); if (save) { int i = min(cols, new_cols);