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BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953
Read of size 4 at addr ffff88808846e070 by task syz-executor.2/7751

CPU: 0 PID: 7751 Comm: syz-executor.2 Not tainted 6.4.0-rc7-syzkaller-00194-g8a28a0b6f1a1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:351 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:462
 kasan_report+0x176/0x1b0 mm/kasan/report.c:572
 ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953
 ext4_ext_map_blocks+0x2d1/0x7210 fs/ext4/extents.c:4102
 ext4_map_blocks+0xa4c/0x1cf0 fs/ext4/inode.c:623
 _ext4_get_block+0x238/0x6a0 fs/ext4/inode.c:779
 __block_write_begin_int+0x548/0x1a50 fs/buffer.c:2064
 __block_write_begin fs/buffer.c:2114 [inline]
 block_page_mkwrite+0x2fc/0x620 fs/buffer.c:2588
 ext4_page_mkwrite+0x4ff/0x1290 fs/ext4/inode.c:6142
 do_page_mkwrite+0x1a4/0x600 mm/memory.c:2931
 wp_page_shared mm/memory.c:3280 [inline]
 do_wp_page+0x501/0x3690 mm/memory.c:3362
 handle_pte_fault mm/memory.c:4964 [inline]
 __handle_mm_fault mm/memory.c:5089 [inline]
 handle_mm_fault+0x2371/0x5860 mm/memory.c:5243
 do_user_addr_fault arch/x86/mm/fault.c:1440 [inline]
 handle_page_fault arch/x86/mm/fault.c:1534 [inline]
 exc_page_fault+0x7d2/0x910 arch/x86/mm/fault.c:1590
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x7f867ec86ed6
Code: 4c 29 c7 4c 01 c2 48 3b 15 e7 3f c5 00 0f 87 cc 00 00 00 0f 10 06 0f 10 4e 10 0f 10 56 20 0f 10 5e 30 48 83 c6 40 48 83 ea 40 <0f> 29 07 0f 29 4f 10 0f 29 57 20 0f 29 5f 30 48 83 c7 40 48 83 fa
RSP: 002b:00007ffc555c9d18 EFLAGS: 00010202
RAX: 0000000020003600 RBX: 0000000000000000 RCX: 0000000020003719
RDX: 00000000000000d9 RSI: 00007f867e8210a0 RDI: 0000000020003610
RBP: 00007ffc555c9dd8 R08: fffffffffffffff0 R09: 00007f867e800000
R10: 00007f867e821038 R11: 0000000020003600 R12: 00000000000621a2
R13: 00007ffc555c9e00 R14: 00007f867edabf80 R15: 0000000000000032
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0002211b80 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x1 pfn:0x8846e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffff7f(buddy)
raw: 00fff00000000000 ffffea0002116808 ffffea000212b988 0000000000000000
raw: 0000000000000001 0000000000000001 00000000ffffff7f 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 7665, tgid 7664 (syz-executor.3), ts 398978330424, free_ts 401288845137
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1731
 prep_new_page mm/page_alloc.c:1738 [inline]
 get_page_from_freelist+0x321c/0x33a0 mm/page_alloc.c:3502
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4768
 __folio_alloc+0x13/0x30 mm/page_alloc.c:4800
 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2240
 shmem_alloc_folio mm/shmem.c:1579 [inline]
 shmem_alloc_and_acct_folio+0x5e7/0xe10 mm/shmem.c:1603
 shmem_get_folio_gfp+0x120f/0x3470 mm/shmem.c:1948
 shmem_get_folio mm/shmem.c:2079 [inline]
 shmem_write_begin+0x172/0x4e0 mm/shmem.c:2573
 generic_perform_write+0x300/0x5e0 mm/filemap.c:3929
 __generic_file_write_iter+0x17a/0x400 mm/filemap.c:4057
 generic_file_write_iter+0xaf/0x310 mm/filemap.c:4089
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x790/0xb20 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1302 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2564
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2705
 release_pages+0x2193/0x2470 mm/swap.c:1042
 __pagevec_release+0x84/0x100 mm/swap.c:1062
 pagevec_release include/linux/pagevec.h:63 [inline]
 folio_batch_release include/linux/pagevec.h:132 [inline]
 shmem_undo_range+0x6af/0x1ba0 mm/shmem.c:954
 shmem_truncate_range mm/shmem.c:1049 [inline]
 shmem_evict_inode+0x258/0x9f0 mm/shmem.c:1164
 evict+0x2a4/0x620 fs/inode.c:665
 __dentry_kill+0x436/0x650 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x1f3/0x420 fs/dcache.c:913
 __fput+0x5e4/0x890 fs/file_table.c:329
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff88808846df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88808846df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88808846e000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff88808846e080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88808846e100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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