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BUG: KASAN: slab-use-after-free in drm_atomic_helper_wait_for_vblanks+0x367/0x980 drivers/gpu/drm/drm_atomic_helper.c:1815
Read of size 1 at addr ffff88805660d409 by task kworker/u4:9/3095

CPU: 0 UID: 0 PID: 3095 Comm: kworker/u4:9 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound commit_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 drm_atomic_helper_wait_for_vblanks+0x367/0x980 drivers/gpu/drm/drm_atomic_helper.c:1815
 drm_atomic_helper_commit_tail+0x302/0x520 drivers/gpu/drm/drm_atomic_helper.c:1911
 commit_tail+0x29a/0x3a0 drivers/gpu/drm/drm_atomic_helper.c:1988
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6545:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4407
 kmalloc_noprof include/linux/slab.h:905 [inline]
 drm_atomic_helper_crtc_duplicate_state+0x72/0xb0 drivers/gpu/drm/drm_atomic_state_helper.c:178
 drm_atomic_get_crtc_state+0x19a/0x460 drivers/gpu/drm/drm_atomic.c:360
 page_flip_common+0x56/0x2a0 drivers/gpu/drm/drm_atomic_helper.c:3832
 drm_atomic_helper_page_flip+0xa5/0x160 drivers/gpu/drm/drm_atomic_helper.c:3893
 drm_mode_page_flip_ioctl+0xc6d/0x11d0 drivers/gpu/drm/drm_plane.c:1543
 drm_ioctl_kernel+0x2cf/0x390 drivers/gpu/drm/drm_ioctl.c:796
 drm_ioctl+0x67f/0xb10 drivers/gpu/drm/drm_ioctl.c:893
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2422 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x18e/0x440 mm/slub.c:4894
 drm_atomic_state_default_clear+0x41f/0xbe0 drivers/gpu/drm/drm_atomic.c:224
 drm_atomic_state_clear drivers/gpu/drm/drm_atomic.c:293 [inline]
 __drm_atomic_state_free+0xaf/0x210 drivers/gpu/drm/drm_atomic.c:310
 kref_put include/linux/kref.h:65 [inline]
 drm_atomic_state_put include/drm/drm_atomic.h:588 [inline]
 drm_atomic_helper_dirtyfb+0xe2d/0xee0 drivers/gpu/drm/drm_damage_helper.c:195
 drm_fbdev_shmem_helper_fb_dirty+0x160/0x2f0 drivers/gpu/drm/drm_fbdev_shmem.c:118
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:380 [inline]
 drm_fb_helper_damage_work+0x224/0x710 drivers/gpu/drm/drm_fb_helper.c:403
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88805660d400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 9 bytes inside of
 freed 512-byte region [ffff88805660d400, ffff88805660d600)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5660c
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 04fff00000000001 ffffea0001598301 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5449, tgid 5449 (syz-executor), ts 151190717606, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2660
 new_slab mm/slub.c:2714 [inline]
 ___slab_alloc+0xbeb/0x1420 mm/slub.c:3901
 __slab_alloc mm/slub.c:3992 [inline]
 __slab_alloc_node mm/slub.c:4067 [inline]
 slab_alloc_node mm/slub.c:4228 [inline]
 __do_kmalloc_node mm/slub.c:4375 [inline]
 __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4388
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3811
 ip6_route_add+0x49/0x1b0 net/ipv6/route.c:3940
 addrconf_add_mroute net/ipv6/addrconf.c:2552 [inline]
 addrconf_add_dev+0x24f/0x340 net/ipv6/addrconf.c:2570
 inet6_addr_add+0x1a1/0xc00 net/ipv6/addrconf.c:3032
 inet6_rtm_newaddr+0x93d/0xd20 net/ipv6/addrconf.c:5059
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6946
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88805660d300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805660d380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805660d400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88805660d480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805660d500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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