================================================================== BUG: KASAN: use-after-free in fb_mode_is_equal+0x36e/0x5e0 drivers/video/fbdev/core/modedb.c:924 Read of size 4 at addr ffff888145a10f1c by task syz-executor.4/18852 CPU: 1 PID: 18852 Comm: syz-executor.4 Not tainted 5.13.0-rc5-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+0x202/0x31e lib/dump_stack.c:120 print_address_description+0x5f/0x3b0 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report+0x15c/0x200 mm/kasan/report.c:436 fb_mode_is_equal+0x36e/0x5e0 drivers/video/fbdev/core/modedb.c:924 fbcon_mode_deleted+0x16b/0x220 drivers/video/fbdev/core/fbcon.c:2718 fb_set_var+0x241/0xdf0 drivers/video/fbdev/core/fbmem.c:975 do_fb_ioctl+0x586/0x7e0 drivers/video/fbdev/core/fbmem.c:1108 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055 do_syscall_64+0x3f/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:00007faec1b7d188 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: 00007ffeb937d3bf R14: 00007faec1b7d300 R15: 0000000000022000 Allocated by task 1: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:428 [inline] ____kasan_kmalloc+0xc4/0xf0 mm/kasan/common.c:507 kasan_kmalloc include/linux/kasan.h:246 [inline] kmem_cache_alloc_trace+0x96/0x340 mm/slub.c:2940 kmalloc include/linux/slab.h:556 [inline] fb_add_videomode+0x6f9/0x800 drivers/video/fbdev/core/modedb.c:1073 do_register_framebuffer drivers/video/fbdev/core/fbmem.c:1637 [inline] register_framebuffer+0x6d3/0xa30 drivers/video/fbdev/core/fbmem.c:1821 __drm_fb_helper_initial_config_and_unlock+0x12e8/0x1cf0 drivers/gpu/drm/drm_fb_helper.c:1855 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1921 [inline] drm_fbdev_client_hotplug+0x66c/0x7f0 drivers/gpu/drm/drm_fb_helper.c:2423 drm_fbdev_generic_setup+0x191/0x400 drivers/gpu/drm/drm_fb_helper.c:2510 vkms_create drivers/gpu/drm/vkms/vkms_drv.c:178 [inline] vkms_init+0x5a3/0x6fc drivers/gpu/drm/vkms/vkms_drv.c:202 do_one_initcall+0x1a7/0x400 init/main.c:1249 do_initcall_level+0x14a/0x1f5 init/main.c:1322 do_initcalls+0x4b/0x8c init/main.c:1338 kernel_init_freeable+0x3fd/0x58a init/main.c:1560 kernel_init+0xd/0x290 init/main.c:1447 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Freed by task 18842: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x3d/0x70 mm/kasan/common.c:46 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:357 ____kasan_slab_free+0x109/0x150 mm/kasan/common.c:360 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1582 [inline] slab_free_freelist_hook+0x1d8/0x290 mm/slub.c:1607 slab_free mm/slub.c:3167 [inline] kfree+0xcf/0x2d0 mm/slub.c:4217 fb_delete_videomode+0x56a/0x820 drivers/video/fbdev/core/modedb.c:1104 fb_set_var+0x253/0xdf0 drivers/video/fbdev/core/fbmem.c:978 do_fb_ioctl+0x586/0x7e0 drivers/video/fbdev/core/fbmem.c:1108 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff888145a10f00 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 28 bytes inside of 96-byte region [ffff888145a10f00, ffff888145a10f60) The buggy address belongs to the page: page:ffffea0005168400 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888145a10200 pfn:0x145a10 flags: 0x57ff00000000200(slab|node=1|zone=2|lastcpupid=0x7ff) raw: 057ff00000000200 ffffea0005096dc8 ffffea000508fb08 ffff888011841780 raw: ffff888145a10200 000000000020001a 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 7064447293, free_ts 0 prep_new_page mm/page_alloc.c:2358 [inline] get_page_from_freelist+0x779/0xa20 mm/page_alloc.c:3994 __alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5200 alloc_page_interleave+0x22/0x1b0 mm/mempolicy.c:2147 alloc_slab_page mm/slub.c:1645 [inline] allocate_slab+0xf1/0x5b0 mm/slub.c:1785 new_slab mm/slub.c:1848 [inline] new_slab_objects mm/slub.c:2594 [inline] ___slab_alloc+0x1cf/0x350 mm/slub.c:2757 __slab_alloc mm/slub.c:2797 [inline] slab_alloc_node mm/slub.c:2879 [inline] slab_alloc mm/slub.c:2921 [inline] kmem_cache_alloc_trace+0x2a3/0x340 mm/slub.c:2938 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:686 [inline] acpi_os_allocate_zeroed include/acpi/platform/aclinuxex.h:57 [inline] acpi_evaluate_object+0x10b/0xa0d drivers/acpi/acpica/nsxfeval.c:177 acpi_evaluate_integer+0x111/0x300 drivers/acpi/utils.c:260 acpi_bus_get_status_handle drivers/acpi/bus.c:81 [inline] acpi_bus_get_status+0x142/0x340 drivers/acpi/bus.c:110 acpi_serdev_check_resources drivers/tty/serdev/core.c:625 [inline] acpi_serdev_add_device+0x187/0x840 drivers/tty/serdev/core.c:700 acpi_ns_walk_namespace+0x246/0x4ab drivers/acpi/acpica/nswalk.c:230 acpi_walk_namespace+0xe8/0x117 drivers/acpi/acpica/nsxfeval.c:606 acpi_serdev_register_devices drivers/tty/serdev/core.c:714 [inline] serdev_controller_add+0xc5/0x210 drivers/tty/serdev/core.c:754 serdev_tty_port_register+0x15d/0x250 drivers/tty/serdev/serdev-ttyport.c:289 tty_port_register_device_attr_serdev+0xcd/0x140 drivers/tty/tty_port.c:162 uart_add_one_port+0xb27/0x17b0 drivers/tty/serial/serial_core.c:2928 page_owner free stack trace missing Memory state around the buggy address: ffff888145a10e00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff888145a10e80: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc >ffff888145a10f00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888145a10f80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc ffff888145a11000: fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb fb ==================================================================