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BUG: KASAN: use-after-free in f2fs_available_free_memory+0xa98/0xb00 fs/f2fs/node.c:99
Read of size 4 at addr ffff88810e9a7c10 by task f2fs_discard-7:/8436

CPU: 0 PID: 8436 Comm: f2fs_discard-7: Not tainted 5.10.89-syzkaller-00788-g9b28b48fb343 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x8d/0x3d0 mm/kasan/report.c:233
 __kasan_report+0x142/0x220 mm/kasan/report.c:419
 kasan_report+0x51/0x70 mm/kasan/report.c:436
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 f2fs_available_free_memory+0xa98/0xb00 fs/f2fs/node.c:99
 issue_discard_thread+0x2dd/0x1b00 fs/f2fs/segment.c:1761
 kthread+0x371/0x390 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Allocated by task 8420:
 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+0xdc/0x110 mm/kasan/common.c:507
 __kasan_kmalloc+0x9/0x10 mm/kasan/common.c:516
 kasan_kmalloc include/linux/kasan.h:269 [inline]
 kmem_cache_alloc_trace+0x210/0x3a0 mm/slub.c:2975
 kmalloc include/linux/slab.h:552 [inline]
 f2fs_kmalloc fs/f2fs/f2fs.h:3167 [inline]
 f2fs_kzalloc fs/f2fs/f2fs.h:3173 [inline]
 f2fs_build_node_manager+0x57/0x1390 fs/f2fs/node.c:3212
 f2fs_fill_super+0x6447/0x8f90 fs/f2fs/super.c:3992
 mount_bdev+0x25f/0x370 fs/super.c:1419
 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4258
 legacy_get_tree+0xf0/0x190 fs/fs_context.c:592
 vfs_get_tree+0x89/0x270 fs/super.c:1549
 do_new_mount fs/namespace.c:2899 [inline]
 path_mount+0x1975/0x2ab0 fs/namespace.c:3229
 do_mount fs/namespace.c:3242 [inline]
 __do_sys_mount fs/namespace.c:3450 [inline]
 __se_sys_mount+0x2f7/0x3b0 fs/namespace.c:3427
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3427
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 8420:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:46
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:357
 ____kasan_slab_free+0x133/0x170 mm/kasan/common.c:360
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:368
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:1596 [inline]
 slab_free_freelist_hook+0xcc/0x1a0 mm/slub.c:1622
 slab_free mm/slub.c:3204 [inline]
 kfree+0xd5/0x320 mm/slub.c:4192
 f2fs_destroy_node_manager+0xdfd/0xf60 fs/f2fs/node.c:3305
 f2fs_fill_super+0x7475/0x8f90 fs/f2fs/super.c:4203
 mount_bdev+0x25f/0x370 fs/super.c:1419
 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4258
 legacy_get_tree+0xf0/0x190 fs/fs_context.c:592
 vfs_get_tree+0x89/0x270 fs/super.c:1549
 do_new_mount fs/namespace.c:2899 [inline]
 path_mount+0x1975/0x2ab0 fs/namespace.c:3229
 do_mount fs/namespace.c:3242 [inline]
 __do_sys_mount fs/namespace.c:3450 [inline]
 __se_sys_mount+0x2f7/0x3b0 fs/namespace.c:3427
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3427
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88810e9a7c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 16 bytes inside of
 512-byte region [ffff88810e9a7c00, ffff88810e9a7e00)
The buggy address belongs to the page:
page:ffffea00043a6900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10e9a4
head:ffffea00043a6900 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 ffffea0004341400 0000000300000003 ffff888100043080
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x152a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 74, ts 331215856380, free_ts 331138087770
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2385 [inline]
 prep_new_page mm/page_alloc.c:2391 [inline]
 get_page_from_freelist+0xa74/0xa90 mm/page_alloc.c:4063
 __alloc_pages_nodemask+0x3c8/0x820 mm/page_alloc.c:5106
 alloc_slab_page mm/slub.c:1807 [inline]
 allocate_slab+0x6b/0x350 mm/slub.c:1809
 new_slab mm/slub.c:1870 [inline]
 new_slab_objects mm/slub.c:2629 [inline]
 ___slab_alloc+0x143/0x2f0 mm/slub.c:2792
 __slab_alloc mm/slub.c:2832 [inline]
 slab_alloc_node mm/slub.c:2914 [inline]
 slab_alloc mm/slub.c:2956 [inline]
 __kmalloc+0x2af/0x3d0 mm/slub.c:4030
 kmalloc include/linux/slab.h:557 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 neigh_alloc net/core/neighbour.c:406 [inline]
 ___neigh_create+0x608/0x1a50 net/core/neighbour.c:590
 __neigh_create+0x32/0x40 net/core/neighbour.c:678
 ip6_finish_output2+0xa11/0x1930 net/ipv6/ip6_output.c:142
 __ip6_finish_output+0x610/0x7b0 net/ipv6/ip6_output.c:210
 ip6_finish_output+0x3f/0x1e0 net/ipv6/ip6_output.c:220
 NF_HOOK_COND include/linux/netfilter.h:293 [inline]
 ip6_output+0x211/0x4c0 net/ipv6/ip6_output.c:243
 dst_output include/net/dst.h:443 [inline]
 NF_HOOK include/linux/netfilter.h:304 [inline]
 ndisc_send_skb+0x6fe/0xc10 net/ipv6/ndisc.c:508
 ndisc_send_rs+0x522/0x690 net/ipv6/ndisc.c:702
 addrconf_dad_completed+0x8ee/0xdc0 net/ipv6/addrconf.c:4224
 addrconf_dad_work+0xe4b/0x1d40 net/ipv6/addrconf.c:3989
 process_one_work+0x6b4/0xfb0 kernel/workqueue.c:2289
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1331 [inline]
 __free_pages_ok+0xbe7/0xc20 mm/page_alloc.c:1611
 free_the_page mm/page_alloc.c:5167 [inline]
 __free_pages+0x2d6/0x4a0 mm/page_alloc.c:5173
 __free_slab+0xdf/0x1a0 mm/slub.c:1895
 free_slab mm/slub.c:1910 [inline]
 discard_slab mm/slub.c:1916 [inline]
 unfreeze_partials+0x17d/0x1b0 mm/slub.c:2410
 put_cpu_partial+0xc8/0x190 mm/slub.c:2446
 __slab_free+0x2eb/0x4e0 mm/slub.c:3096
 do_slab_free mm/slub.c:3192 [inline]
 ___cache_free+0x131/0x150 mm/slub.c:3211
 qlink_free+0x38/0x40 mm/kasan/quarantine.c:146
 qlist_free_all mm/kasan/quarantine.c:165 [inline]
 kasan_quarantine_reduce+0x178/0x1d0 mm/kasan/quarantine.c:272
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:438
 kasan_slab_alloc include/linux/kasan.h:259 [inline]
 slab_post_alloc_hook mm/slab.h:583 [inline]
 slab_alloc_node mm/slub.c:2948 [inline]
 slab_alloc mm/slub.c:2956 [inline]
 kmem_cache_alloc_trace+0x1a5/0x3a0 mm/slub.c:2973
 kmalloc include/linux/slab.h:552 [inline]
 __kthread_create_on_node+0x11f/0x410 kernel/kthread.c:358
 kthread_create_on_node+0xda/0x120 kernel/kthread.c:447
 loop_prepare_queue drivers/block/loop.c:931 [inline]
 loop_configure+0x702/0x15b0 drivers/block/loop.c:1124
 lo_ioctl+0x821/0x2380 drivers/block/loop.c:1690
 __blkdev_driver_ioctl block/ioctl.c:237 [inline]
 blkdev_ioctl+0x2c3/0x5f0 block/ioctl.c:632

Memory state around the buggy address:
 ffff88810e9a7b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810e9a7b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810e9a7c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88810e9a7c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810e9a7d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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