KASAN: stack-out-of-bounds Write in sys

KASAN: stack-out-of-bounds Write in sys_imageblit
Status: upstream: reported on 2020/07/21 04:42
Reported-by: syzbot+ba5bd977df7bb87862c4@syzkaller.appspotmail.com
First crash: 182d, last: 84d

Sample crash report:

==================================================================
BUG: KASAN: stack-out-of-bounds in fast_imageblit drivers/video/fbdev/core/sysimgblt.c:229 [inline]
BUG: KASAN: stack-out-of-bounds in sys_imageblit+0x117f/0x1290 drivers/video/fbdev/core/sysimgblt.c:275
Write of size 4 at addr ffffc9000bdd7d90 by task syz-executor.0/24135

CPU: 0 PID: 24135 Comm: syz-executor.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
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+0x5/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 fast_imageblit drivers/video/fbdev/core/sysimgblt.c:229 [inline]
 sys_imageblit+0x117f/0x1290 drivers/video/fbdev/core/sysimgblt.c:275
 drm_fb_helper_sys_imageblit+0x1c/0x180 drivers/gpu/drm/drm_fb_helper.c:767
 bit_putcs_unaligned drivers/video/fbdev/core/bitblit.c:139 [inline]
 bit_putcs+0x6e1/0xd20 drivers/video/fbdev/core/bitblit.c:188
 fbcon_putcs+0x35a/0x450 drivers/video/fbdev/core/fbcon.c:1306
 do_update_region+0x399/0x630 drivers/tty/vt/vt.c:676
 invert_screen+0x1d4/0x600 drivers/tty/vt/vt.c:800
 highlight drivers/tty/vt/selection.c:57 [inline]
 clear_selection drivers/tty/vt/selection.c:84 [inline]
 clear_selection+0x55/0x70 drivers/tty/vt/selection.c:80
 vc_do_resize+0xe63/0x1150 drivers/tty/vt/vt.c:1241
 fbcon_do_set_font+0x48e/0x880 drivers/video/fbdev/core/fbcon.c:2442
 fbcon_set_font+0x7c9/0x9b0 drivers/video/fbdev/core/fbcon.c:2537
 con_font_set drivers/tty/vt/vt.c:4667 [inline]
 con_font_op+0xd0c/0x1110 drivers/tty/vt/vt.c:4732
 vt_io_ioctl drivers/tty/vt/vt_ioctl.c:594 [inline]
 vt_ioctl+0x1ab2/0x2bc0 drivers/tty/vt/vt_ioctl.c:818
 vt_compat_ioctl+0x168/0x6f0 drivers/tty/vt/vt_ioctl.c:1226
 tty_compat_ioctl+0x19c/0x410 drivers/tty/tty_io.c:2845
 __do_compat_sys_ioctl+0x1d3/0x230 fs/ioctl.c:842
 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline]
 __do_fast_syscall_32+0x56/0x80 arch/x86/entry/common.c:137
 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7fc1549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f55bb0bc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004b61
RDX: 0000000020000080 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000


Memory state around the buggy address:
 ffffc9000bdd7c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000bdd7d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000bdd7d80: 00 00 f1 f1 f1 f1 00 00 f3 f3 00 00 00 00 00 00
                         ^
 ffffc9000bdd7e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000bdd7e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-qemu-upstream-386	2020/10/27 10:12	upstream	4525c878	94942294	.config	log	report			info	b.zolnierkie@samsung.com, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
ci-qemu-upstream-386	2020/07/21 00:07	upstream	4fa640dc	8caeeeb7	.config	log	report				b.zolnierkie@samsung.com, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org