==================================================================
BUG: KASAN: slab-use-after-free in ptep_get include/linux/pgtable.h:340 [inline]
BUG: KASAN: slab-use-after-free in filemap_map_folio_range mm/filemap.c:3666 [inline]
BUG: KASAN: slab-use-after-free in filemap_map_pages+0x13de/0x1670 mm/filemap.c:3783
Read of size 8 at addr ffff88805da00000 by task syz.2.764/8099

CPU: 1 UID: 0 PID: 8099 Comm: syz.2.764 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ptep_get include/linux/pgtable.h:340 [inline]
 filemap_map_folio_range mm/filemap.c:3666 [inline]
 filemap_map_pages+0x13de/0x1670 mm/filemap.c:3783
 do_fault_around mm/memory.c:5531 [inline]
 do_read_fault mm/memory.c:5564 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xe39/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x550/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
 mm_populate include/linux/mm.h:3367 [inline]
 vm_mmap_pgoff+0x37f/0x470 mm/util.c:585
 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efffb78eec9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efffc63a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007efffb9e6090 RCX: 00007efffb78eec9
RDX: 00000000027ffff7 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007efffb811f91 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000004012011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efffb9e6128 R14: 00007efffb9e6090 R15: 00007ffc9a195898
 </TASK>

Allocated by task 59:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4376 [inline]
 __kmalloc_node_track_caller_noprof+0x221/0x510 mm/slub.c:4395
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:600
 __alloc_skb+0x166/0x380 net/core/skbuff.c:669
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:763 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline]
 nsim_dev_trap_report_work+0x2b1/0xcf0 drivers/net/netdevsim/dev.c:866
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 59:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x60/0x70 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+0x2b4/0x4d0 mm/slub.c:4894
 skb_kfree_head net/core/skbuff.c:1047 [inline]
 skb_free_head+0x114/0x210 net/core/skbuff.c:1059
 skb_release_data+0x795/0x9e0 net/core/skbuff.c:1086
 skb_release_all net/core/skbuff.c:1151 [inline]
 __kfree_skb net/core/skbuff.c:1165 [inline]
 consume_skb net/core/skbuff.c:1397 [inline]
 consume_skb+0xbf/0x100 net/core/skbuff.c:1391
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:836 [inline]
 nsim_dev_trap_report_work+0x8bd/0xcf0 drivers/net/netdevsim/dev.c:866
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 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 ffff88805da00000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 0 bytes inside of
 freed 4096-byte region [ffff88805da00000, ffff88805da01000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5da00
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b042140 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b042140 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0001768001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 59, tgid 59 (kworker/u8:4), ts 212639744364, free_ts 212536345481
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab mm/slub.c:2660 [inline]
 new_slab+0x247/0x330 mm/slub.c:2714
 ___slab_alloc+0xcf2/0x1750 mm/slub.c:3901
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3992
 __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_node_track_caller_noprof+0x2ee/0x510 mm/slub.c:4395
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:600
 __alloc_skb+0x166/0x380 net/core/skbuff.c:669
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:763 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline]
 nsim_dev_trap_report_work+0x2b1/0xcf0 drivers/net/netdevsim/dev.c:866
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5837 tgid 5837 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0x7d5/0x10f0 mm/page_alloc.c:2895
 discard_slab mm/slub.c:2758 [inline]
 __put_partials+0x165/0x1c0 mm/slub.c:3223
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4191 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4247
 ptlock_alloc+0x1f/0x70 mm/memory.c:7161
 ptlock_init include/linux/mm.h:2953 [inline]
 pagetable_pte_ctor include/linux/mm.h:3002 [inline]
 __pte_alloc_one_noprof include/asm-generic/pgalloc.h:78 [inline]
 pte_alloc_one+0x82/0x3a0 arch/x86/mm/pgtable.c:18
 __pte_alloc+0x6d/0x3c0 mm/memory.c:452
 copy_pte_range mm/memory.c:1107 [inline]
 copy_pmd_range mm/memory.c:1261 [inline]
 copy_pud_range mm/memory.c:1298 [inline]
 copy_p4d_range mm/memory.c:1322 [inline]
 copy_page_range+0x3b83/0x5c80 mm/memory.c:1410
 dup_mmap+0xe87/0x21d0 mm/mmap.c:1834
 dup_mm kernel/fork.c:1486 [inline]
 copy_mm kernel/fork.c:1538 [inline]
 copy_process+0x4099/0x76a0 kernel/fork.c:2180
 kernel_clone+0xfc/0x930 kernel/fork.c:2610
 __do_sys_clone+0xce/0x120 kernel/fork.c:2753
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805d9fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805d9fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805da00000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88805da00080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805da00100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
page: refcount:6 mapcount:1 mapping:ffff888077176458 index:0x2 pfn:0x695f8
head: order:1 mapcount:2 entire_mapcount:0 nr_pages_mapped:2 pincount:0
memcg:ffff8881404d1a00
aops:ext4_da_aops ino:f dentry name(?):"file1"
flags: 0xfff20000004079(locked|uptodate|dirty|lru|private|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff20000004079 ffffea0001fff408 ffffea0001312308 ffff888077176458
raw: 0000000000000002 ffff88806b622ae0 0000000600000000 ffff8881404d1a00
head: 00fff20000004079 ffffea0001fff408 ffffea0001312308 ffff888077176458
head: 0000000000000002 ffff88806b622ae0 0000000600000000 ffff8881404d1a00
head: 00fff00000000201 ffffea0001a57e01 0000000200000001 00000000ffffffff
head: ffffffff00000001 000000000000000e 0000000000000000 0000000000000002
page dumped because: VM_WARN_ON_FOLIO((_Generic((page), const struct page *: (const struct folio *)_compound_head(page), struct page *: (struct folio *)_compound_head(page))) != folio)
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Movable, gfp_mask 0x153cca(GFP_HIGHUSER_MOVABLE|__GFP_WRITE|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 8089, tgid 8088 (syz.2.764), ts 218805459130, free_ts 216075252725
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_pages_noprof mm/mempolicy.c:2507 [inline]
 folio_alloc_noprof+0x20/0x2d0 mm/mempolicy.c:2517
 filemap_alloc_folio_noprof+0x3a1/0x470 mm/filemap.c:1007
 __filemap_get_folio+0x4a8/0xc30 mm/filemap.c:1981
 write_begin_get_folio include/linux/pagemap.h:776 [inline]
 ext4_da_write_begin+0x4f1/0xcc0 fs/ext4/inode.c:3145
 generic_perform_write+0x3c4/0x900 mm/filemap.c:4175
 ext4_buffered_write_iter+0x119/0x440 fs/ext4/file.c:299
 ext4_file_write_iter+0xa4c/0x1d10 fs/ext4/file.c:723
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x7d3/0x11d0 fs/read_write.c:686
 ksys_pwrite64 fs/read_write.c:793 [inline]
 __do_sys_pwrite64 fs/read_write.c:801 [inline]
 __se_sys_pwrite64 fs/read_write.c:798 [inline]
 __x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:798
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 8025 tgid 8024 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:999
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1914 [inline]
 iput.part.0+0x6a9/0xb00 fs/inode.c:1966
 iput+0x35/0x40 fs/inode.c:1929
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 fput_close_sync+0x118/0x210 fs/file_table.c:573
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close fs/open.c:1572 [inline]
 __x64_sys_close+0x8b/0x120 fs/open.c:1572
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
------------[ cut here ]------------
WARNING: CPU: 1 PID: 8099 at ./include/linux/rmap.h:426 __folio_rmap_sanity_checks+0x51f/0x770 include/linux/rmap.h:426
Modules linked in:
CPU: 1 UID: 0 PID: 8099 Comm: syz.2.764 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__folio_rmap_sanity_checks+0x51f/0x770 include/linux/rmap.h:426
Code: 63 ad ff 49 83 ee 01 e8 af 63 ad ff 49 39 de 0f 84 3b fc ff ff e8 a1 63 ad ff 48 c7 c6 60 ea 7b 8b 48 89 df e8 a2 2e f6 ff 90 <0f> 0b 90 e9 1e fc ff ff e8 84 63 ad ff 31 f6 48 89 df e8 da c6 ff
RSP: 0018:ffffc9000b5975a8 EFLAGS: 00010246
RAX: 0000000000080000 RBX: ffffea0001a57e00 RCX: ffffc9001c6e1000
RDX: 0000000000080000 RSI: ffffffff820db52e RDI: ffff8880344cdf44
RBP: ffffea0001a58180 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 535f7972746e6520 R12: 00000000000001f0
R13: 0000000000000000 R14: ffffea0001a58180 R15: 0000000000000000
FS:  00007efffc63a6c0(0000) GS:ffff888124f72000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000f000 CR3: 0000000029133000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __folio_add_rmap mm/rmap.c:1252 [inline]
 __folio_add_file_rmap mm/rmap.c:1620 [inline]
 folio_add_file_rmap_ptes+0x77/0x840 mm/rmap.c:1642
 set_pte_range+0x214/0x740 mm/memory.c:5311
 filemap_map_folio_range mm/filemap.c:3673 [inline]
 filemap_map_pages+0x920/0x1670 mm/filemap.c:3783
 do_fault_around mm/memory.c:5531 [inline]
 do_read_fault mm/memory.c:5564 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xe39/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x550/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
 mm_populate include/linux/mm.h:3367 [inline]
 vm_mmap_pgoff+0x37f/0x470 mm/util.c:585
 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efffb78eec9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efffc63a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007efffb9e6090 RCX: 00007efffb78eec9
RDX: 00000000027ffff7 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007efffb811f91 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000004012011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efffb9e6128 R14: 00007efffb9e6090 R15: 00007ffc9a195898
 </TASK>