KASAN: vmalloc-out-of-bounds Write in drm_fb_helper_dirty

KASAN: vmalloc-out-of-bounds Write in drm_fb_helper_dirty_work (3)
Status: upstream: reported on 2020/10/31 11:28
Reported-by: syzbot+58a9f453b90c4bfab018@syzkaller.appspotmail.com
First crash: 84d, last: 84d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: vmalloc-out-of-bounds Write in drm_fb_helper_dirty_work				2	380d	392d	0/17	auto-closed as invalid on 2020/05/04 00:35
upstream	KASAN: vmalloc-out-of-bounds Write in drm_fb_helper_dirty_work (2)				1	253d	253d	0/17	auto-closed as invalid on 2020/09/07 16:23

Sample crash report:

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in memcpy include/linux/string.h:399 [inline]
BUG: KASAN: vmalloc-out-of-bounds in drm_fb_helper_dirty_blit_real drivers/gpu/drm/drm_fb_helper.c:403 [inline]
BUG: KASAN: vmalloc-out-of-bounds in drm_fb_helper_dirty_work+0x42e/0x810 drivers/gpu/drm/drm_fb_helper.c:435
Write of size 4096 at addr ffffc90009bd1000 by task kworker/2:0/23

CPU: 2 PID: 23 Comm: kworker/2:0 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Workqueue: events drm_fb_helper_dirty_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x497 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 memcpy+0x39/0x60 mm/kasan/common.c:106
 memcpy include/linux/string.h:399 [inline]
 drm_fb_helper_dirty_blit_real drivers/gpu/drm/drm_fb_helper.c:403 [inline]
 drm_fb_helper_dirty_work+0x42e/0x810 drivers/gpu/drm/drm_fb_helper.c:435
 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296


Memory state around the buggy address:
 ffffc90009bd0f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90009bd0f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90009bd1000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc90009bd1080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90009bd1100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-qemu-upstream	2020/10/27 10:38	upstream	4525c878	94942294	.config	log	report			info	airlied@linux.ie, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de