================================================================== 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 ffff8881443a211c by task syz-executor.5/30841 CPU: 0 PID: 30841 Comm: syz-executor.5 Not tainted 5.14.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x83/0xdf 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_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 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:00007f97b0965188 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: 00007f97b0965300 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:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:591 [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+0xd80/0x1300 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+0x32c/0x590 drivers/gpu/drm/drm_fb_helper.c:2423 drm_fbdev_generic_setup+0x1cc/0x460 drivers/gpu/drm/drm_fb_helper.c:2510 vkms_create drivers/gpu/drm/vkms/vkms_drv.c:182 [inline] vkms_init+0x591/0x615 drivers/gpu/drm/vkms/vkms_drv.c:207 do_one_initcall+0x103/0x650 init/main.c:1282 do_initcall_level init/main.c:1355 [inline] do_initcalls init/main.c:1371 [inline] do_basic_setup init/main.c:1391 [inline] kernel_init_freeable+0x6b8/0x741 init/main.c:1593 kernel_init+0x1a/0x1d0 init/main.c:1485 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Freed by task 30825: 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:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:229 [inline] slab_free_hook mm/slub.c:1650 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1675 slab_free mm/slub.c:3235 [inline] kfree+0xeb/0x650 mm/slub.c:4295 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_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff8881443a2100 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 28 bytes inside of 96-byte region [ffff8881443a2100, ffff8881443a2160) The buggy address belongs to the page: page:ffffea000510e880 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8881443a2700 pfn:0x1443a2 flags: 0x57ff00000000200(slab|node=1|zone=2|lastcpupid=0x7ff) raw: 057ff00000000200 ffffea000519ee88 ffffea0005176408 ffff888010841780 raw: ffff8881443a2700 000000000020001d 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 8137561433, free_ts 0 prep_new_page mm/page_alloc.c:2433 [inline] get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5374 alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2119 alloc_pages+0x238/0x2a0 mm/mempolicy.c:2242 alloc_slab_page mm/slub.c:1713 [inline] allocate_slab+0x32b/0x4c0 mm/slub.c:1853 new_slab mm/slub.c:1916 [inline] new_slab_objects mm/slub.c:2662 [inline] ___slab_alloc+0x4ba/0x820 mm/slub.c:2825 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2865 slab_alloc_node mm/slub.c:2947 [inline] slab_alloc mm/slub.c:2989 [inline] kmem_cache_alloc_trace+0x30f/0x3c0 mm/slub.c:3006 kmalloc include/linux/slab.h:591 [inline] kzalloc include/linux/slab.h:721 [inline] kbd_connect+0x44/0x160 drivers/tty/vt/keyboard.c:1569 input_attach_handler+0x180/0x1f0 drivers/input/input.c:1035 input_register_device.cold+0xf0/0x304 drivers/input/input.c:2335 acpi_button_add+0x526/0xac0 drivers/acpi/button.c:548 acpi_device_probe+0xc4/0x3d0 drivers/acpi/bus.c:994 call_driver_probe drivers/base/dd.c:517 [inline] really_probe+0x23c/0xcd0 drivers/base/dd.c:595 __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:747 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:777 page_owner free stack trace missing Memory state around the buggy address: ffff8881443a2000: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc ffff8881443a2080: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc >ffff8881443a2100: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff8881443a2180: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc ffff8881443a2200: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ==================================================================