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BUG: KASAN: use-after-free in fbcon_cursor+0x4e0/0x650 drivers/video/fbdev/core/fbcon.c:1389
Read of size 2 at addr ffff888218f8d222 by task syz-executor.3/17468
CPU: 0 PID: 17468 Comm: syz-executor.3 Not tainted 5.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
__kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
kasan_report+0x33/0x50 mm/kasan/common.c:625
fbcon_cursor+0x4e0/0x650 drivers/video/fbdev/core/fbcon.c:1389
fbcon_scrolldelta+0x669/0x11f0 drivers/video/fbdev/core/fbcon.c:2886
fbcon_set_origin+0x3c/0x50 drivers/video/fbdev/core/fbcon.c:2937
set_origin+0xe7/0x3e0 drivers/tty/vt/vt.c:920
vc_do_resize+0x9df/0x1340 drivers/tty/vt/vt.c:1288
vt_ioctl+0x10d6/0x26b0 drivers/tty/vt/vt_ioctl.c:850
tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc0d4c5fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e9280 RCX: 000000000045c829
RDX: 00000000200000c0 RSI: 0000000000005609 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000041f R14: 00000000004c6bf3 R15: 00007fc0d4c606d4
Allocated by task 1:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
__kasan_kmalloc mm/kasan/common.c:495 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
__do_kmalloc mm/slab.c:3656 [inline]
__kmalloc+0x161/0x7a0 mm/slab.c:3665
kmalloc include/linux/slab.h:560 [inline]
kzalloc include/linux/slab.h:669 [inline]
vc_do_resize+0x245/0x1340 drivers/tty/vt/vt.c:1211
fbcon_init+0x1227/0x1ab0 drivers/video/fbdev/core/fbcon.c:1218
visual_init+0x305/0x5c0 drivers/tty/vt/vt.c:1063
do_bind_con_driver+0x536/0x890 drivers/tty/vt/vt.c:3560
do_take_over_console+0x453/0x5b0 drivers/tty/vt/vt.c:4140
do_fbcon_takeover+0x10b/0x210 drivers/video/fbdev/core/fbcon.c:588
fbcon_fb_registered+0x26b/0x340 drivers/video/fbdev/core/fbcon.c:3261
do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1664 [inline]
register_framebuffer+0x56e/0x980 drivers/video/fbdev/core/fbmem.c:1832
vga16fb_probe+0x6da/0x7ea drivers/video/fbdev/vga16fb.c:1373
platform_drv_probe+0x87/0x140 drivers/base/platform.c:733
really_probe+0x281/0x6d0 drivers/base/dd.c:527
driver_probe_device+0x104/0x210 drivers/base/dd.c:701
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:808
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
__device_attach+0x21a/0x360 drivers/base/dd.c:874
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
device_add+0x132d/0x1bf0 drivers/base/core.c:2533
platform_device_add+0x348/0x6c0 drivers/base/platform.c:583
vga16fb_init+0x152/0x1c8 drivers/video/fbdev/vga16fb.c:1431
do_one_initcall+0x10a/0x7d0 init/main.c:1157
do_initcall_level init/main.c:1230 [inline]
do_initcalls init/main.c:1246 [inline]
do_basic_setup init/main.c:1266 [inline]
kernel_init_freeable+0x501/0x5ae init/main.c:1450
kernel_init+0xd/0x1bb init/main.c:1357
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Freed by task 17468:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
kasan_set_free_info mm/kasan/common.c:317 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
vc_do_resize+0x97f/0x1340 drivers/tty/vt/vt.c:1285
vt_ioctl+0x10d6/0x26b0 drivers/tty/vt/vt_ioctl.c:850
tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
The buggy address belongs to the object at ffff888218f8c000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4642 bytes inside of
8192-byte region [ffff888218f8c000, ffff888218f8e000)
The buggy address belongs to the page:
page:ffffea000863e300 refcount:1 mapcount:0 mapping:00000000a52d0153 index:0x0 head:ffffea000863e300 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x57ffe0000010200(slab|head)
raw: 057ffe0000010200 ffffea000863df08 ffffea00085faf08 ffff8880aa0021c0
raw: 0000000000000000 ffff888218f8c000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888218f8d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888218f8d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888218f8d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888218f8d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888218f8d300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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