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BUG: KASAN: use-after-free in fb_mode_is_equal+0x284/0x2f0 drivers/video/fbdev/core/modedb.c:924
Read of size 4 at addr ffff8880180b6d1c by task syz-executor.4/25766

CPU: 0 PID: 25766 Comm: syz-executor.4 Not tainted 5.13.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436
 fb_mode_is_equal+0x284/0x2f0 drivers/video/fbdev/core/modedb.c:924
 fbcon_mode_deleted+0x13d/0x1d0 drivers/video/fbdev/core/fbcon.c:2718
 fb_set_var+0xae1/0xda0 drivers/video/fbdev/core/fbmem.c:975
 do_fb_ioctl+0x2f9/0x690 drivers/video/fbdev/core/fbmem.c:1108
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbd3421c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000020000040 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 0000000000a9fb1f R14: 00007fbd3421c300 R15: 0000000000022000

Allocated by task 1:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:428 [inline]
 ____kasan_kmalloc mm/kasan/common.c:507 [inline]
 ____kasan_kmalloc mm/kasan/common.c:466 [inline]
 __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516
 kmalloc include/linux/slab.h:556 [inline]
 fb_add_videomode drivers/video/fbdev/core/modedb.c:1073 [inline]
 fb_add_videomode+0x2fb/0x610 drivers/video/fbdev/core/modedb.c:1057
 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1637 [inline]
 register_framebuffer+0x52d/0x9c0 drivers/video/fbdev/core/fbmem.c:1821
 __drm_fb_helper_initial_config_and_unlock+0xd65/0x12f0 drivers/gpu/drm/drm_fb_helper.c:1855
 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1921 [inline]
 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1913 [inline]
 drm_fbdev_client_hotplug+0x2d4/0x580 drivers/gpu/drm/drm_fb_helper.c:2423
 drm_fbdev_generic_setup+0x1c8/0x450 drivers/gpu/drm/drm_fb_helper.c:2510
 vkms_create drivers/gpu/drm/vkms/vkms_drv.c:178 [inline]
 vkms_init+0x55c/0x5e0 drivers/gpu/drm/vkms/vkms_drv.c:202
 do_one_initcall+0x103/0x650 init/main.c:1249
 do_initcall_level init/main.c:1322 [inline]
 do_initcalls init/main.c:1338 [inline]
 do_basic_setup init/main.c:1358 [inline]
 kernel_init_freeable+0x6c4/0x74d init/main.c:1560
 kernel_init+0xd/0x1b8 init/main.c:1447
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Freed by task 25754:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
 ____kasan_slab_free mm/kasan/common.c:360 [inline]
 ____kasan_slab_free mm/kasan/common.c:325 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368
 kasan_slab_free include/linux/kasan.h:212 [inline]
 slab_free_hook mm/slub.c:1583 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1608
 slab_free mm/slub.c:3168 [inline]
 kfree+0xe5/0x7f0 mm/slub.c:4212
 fb_delete_videomode+0x3d2/0x570 drivers/video/fbdev/core/modedb.c:1104
 fb_set_var+0xaf1/0xda0 drivers/video/fbdev/core/fbmem.c:978
 do_fb_ioctl+0x2f9/0x690 drivers/video/fbdev/core/fbmem.c:1108
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff8880180b6d00
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 28 bytes inside of
 96-byte region [ffff8880180b6d00, ffff8880180b6d60)
The buggy address belongs to the page:
page:ffffea0000602d80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x180b6
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888011041780
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 8776748754, free_ts 8692607733
 prep_new_page mm/page_alloc.c:2358 [inline]
 get_page_from_freelist+0x1033/0x2b60 mm/page_alloc.c:3994
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5200
 alloc_page_interleave+0x1e/0x1d0 mm/mempolicy.c:2147
 alloc_pages+0x238/0x2a0 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:1646 [inline]
 allocate_slab+0x2c5/0x4c0 mm/slub.c:1786
 new_slab mm/slub.c:1849 [inline]
 new_slab_objects mm/slub.c:2595 [inline]
 ___slab_alloc+0x4a1/0x810 mm/slub.c:2758
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2798
 slab_alloc_node mm/slub.c:2880 [inline]
 slab_alloc mm/slub.c:2922 [inline]
 __kmalloc+0x315/0x330 mm/slub.c:4050
 acpi_evaluate_object+0x89/0x7f5 drivers/acpi/acpica/nsxfeval.c:177
 acpi_evaluate_integer+0xbf/0x1e0 drivers/acpi/utils.c:260
 acpi_bus_get_status_handle drivers/acpi/bus.c:81 [inline]
 acpi_bus_get_status drivers/acpi/bus.c:110 [inline]
 acpi_bus_get_status+0x18c/0x380 drivers/acpi/bus.c:94
 acpi_serdev_check_resources drivers/tty/serdev/core.c:625 [inline]
 acpi_serdev_add_device+0x17f/0x500 drivers/tty/serdev/core.c:700
 acpi_ns_walk_namespace+0x23d/0x41f drivers/acpi/acpica/nswalk.c:237
 acpi_walk_namespace drivers/acpi/acpica/nsxfeval.c:606 [inline]
 acpi_walk_namespace+0xee/0x127 drivers/acpi/acpica/nsxfeval.c:554
 acpi_serdev_register_devices drivers/tty/serdev/core.c:714 [inline]
 serdev_controller_add+0x23f/0x480 drivers/tty/serdev/core.c:754
 serdev_tty_port_register+0x19a/0x2a0 drivers/tty/serdev/serdev-ttyport.c:289
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1298 [inline]
 free_pcp_prepare+0x223/0x300 mm/page_alloc.c:1342
 free_unref_page_prepare mm/page_alloc.c:3250 [inline]
 free_unref_page+0x12/0x1d0 mm/page_alloc.c:3298
 __vunmap+0x783/0xb60 mm/vmalloc.c:2566
 free_work+0x58/0x70 mm/vmalloc.c:80
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Memory state around the buggy address:
 ffff8880180b6c00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff8880180b6c80: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff8880180b6d00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                            ^
 ffff8880180b6d80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
 ffff8880180b6e00: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
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