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BUG: KASAN: use-after-free in iomap_write_end_inline fs/iomap/buffered-io.c:1032 [inline]
BUG: KASAN: use-after-free in iomap_write_end+0x390/0x720 fs/iomap/buffered-io.c:1050
Write of size 1 at addr ffff88801f4d2a12 by task syz.0.0/5321

CPU: 0 UID: 0 PID: 5321 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 iomap_write_end_inline fs/iomap/buffered-io.c:1032 [inline]
 iomap_write_end+0x390/0x720 fs/iomap/buffered-io.c:1050
 iomap_write_iter fs/iomap/buffered-io.c:1123 [inline]
 iomap_file_buffered_write+0x52b/0xb30 fs/iomap/buffered-io.c:1189
 gfs2_file_buffered_write+0x4eb/0x870 fs/gfs2/file.c:1061
 gfs2_file_write_iter+0x976/0x1130 fs/gfs2/file.c:1166
 iter_file_splice_write+0x99b/0x1100 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1161
 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1230
 do_sendfile+0x535/0x7d0 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1417
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f444e99aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f444f8de028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f444ec16090 RCX: 00007f444e99aeb9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007f444ea08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 000000007ffff004 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f444ec16128 R14: 00007f444ec16090 R15: 00007fffd3e99d98
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x92c pfn:0x1f4d2
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0000456c88 ffffea00007d01c8 0000000000000000
raw: 000000000000092c 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c4a(GFP_NOFS|__GFP_HIGHMEM|__GFP_MOVABLE|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 5321, tgid 5319 (syz.0.0), ts 75374962657, free_ts 76525023907
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 compaction_alloc_noprof mm/compaction.c:1836 [inline]
 compaction_alloc+0x3010/0x3410 mm/compaction.c:1847
 migrate_folio_unmap mm/migrate.c:1214 [inline]
 migrate_pages_batch+0x9e7/0x4d80 mm/migrate.c:1890
 migrate_pages_sync mm/migrate.c:2007 [inline]
 migrate_pages+0x1c95/0x29e0 mm/migrate.c:2116
 compact_zone+0x2140/0x4640 mm/compaction.c:2647
 compact_node+0x21a/0x320 mm/compaction.c:2916
 kcompactd+0xc0f/0x12a0 mm/compaction.c:3214
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
page last free pid 29 tgid 29 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xbf8/0xd70 mm/page_alloc.c:2973
 __folio_put+0x414/0x4f0 mm/swap.c:112
 folio_put include/linux/mm.h:1616 [inline]
 migrate_folio_done mm/migrate.c:1198 [inline]
 migrate_folio_move mm/migrate.c:1412 [inline]
 migrate_folios_move mm/migrate.c:1721 [inline]
 migrate_pages_batch+0x3593/0x4d80 mm/migrate.c:1977
 migrate_pages_sync mm/migrate.c:2007 [inline]
 migrate_pages+0x1c95/0x29e0 mm/migrate.c:2116
 compact_zone+0x2140/0x4640 mm/compaction.c:2647
 compact_node+0x21a/0x320 mm/compaction.c:2916
 kcompactd+0xc0f/0x12a0 mm/compaction.c:3214
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Memory state around the buggy address:
 ffff88801f4d2900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88801f4d2980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88801f4d2a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff88801f4d2a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88801f4d2b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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