================================================================== 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 ffff888016ae121c by task syz-executor.4/9608 CPU: 0 PID: 9608 Comm: syz-executor.4 Not tainted 5.13.0-rc4-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_compat_ioctl+0x17e/0x610 drivers/video/fbdev/core/fbmem.c:1309 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:1167 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] __do_fast_syscall_32+0x67/0xe0 arch/x86/entry/common.c:143 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:168 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf7f6f549 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 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f55695fc EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004601 RDX: 0000000020000040 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 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:1633 [inline] register_framebuffer+0x52d/0x9c0 drivers/video/fbdev/core/fbmem.c:1817 __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+0x643/0x6cc 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 9598: 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:1582 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1607 slab_free mm/slub.c:3167 [inline] kfree+0xe5/0x7f0 mm/slub.c:4217 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_compat_ioctl+0x17e/0x610 drivers/video/fbdev/core/fbmem.c:1309 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:1167 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] __do_fast_syscall_32+0x67/0xe0 arch/x86/entry/common.c:143 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:168 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c The buggy address belongs to the object at ffff888016ae1200 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 28 bytes inside of 96-byte region [ffff888016ae1200, ffff888016ae1260) The buggy address belongs to the page: page:ffffea00005ab840 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16ae1 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea00005ff140 0000000600000002 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 8472264689, free_ts 8471094087 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:1645 [inline] allocate_slab+0x2c5/0x4c0 mm/slub.c:1785 new_slab mm/slub.c:1848 [inline] new_slab_objects mm/slub.c:2594 [inline] ___slab_alloc+0x4a1/0x810 mm/slub.c:2757 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2797 slab_alloc_node mm/slub.c:2879 [inline] __kmalloc_node+0x2e2/0x380 mm/slub.c:4103 kmalloc_node include/linux/slab.h:579 [inline] kvmalloc_node+0x61/0xf0 mm/util.c:587 kvmalloc include/linux/mm.h:804 [inline] kvzalloc include/linux/mm.h:812 [inline] drm_property_create_blob.part.0+0x2f/0x310 drivers/gpu/drm/drm_property.c:567 drm_property_create_blob+0x4a/0x60 drivers/gpu/drm/drm_property.c:564 drm_writeback_connector_init+0xde/0x660 drivers/gpu/drm/drm_writeback.c:187 vkms_output_init+0x393/0x430 drivers/gpu/drm/vkms/vkms_output.c:85 vkms_modeset_init drivers/gpu/drm/vkms/vkms_drv.c:126 [inline] vkms_create drivers/gpu/drm/vkms/vkms_drv.c:170 [inline] vkms_init+0x51c/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+0x643/0x6cc init/main.c:1560 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_list+0x19b/0x7c0 mm/page_alloc.c:3318 release_pages+0x853/0x2120 mm/swap.c:972 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline] tlb_flush_mmu_free mm/mmu_gather.c:242 [inline] tlb_flush_mmu mm/mmu_gather.c:249 [inline] tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:340 exit_mmap+0x2c2/0x590 mm/mmap.c:3210 __mmput+0x122/0x470 kernel/fork.c:1096 mmput+0x58/0x60 kernel/fork.c:1117 free_bprm+0x65/0x2e0 fs/exec.c:1478 kernel_execve+0x380/0x460 fs/exec.c:1975 call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Memory state around the buggy address: ffff888016ae1100: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff888016ae1180: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc >ffff888016ae1200: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888016ae1280: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc ffff888016ae1300: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc ==================================================================