================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:840 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xb92/0xd80 fs/ext4/extents.c:955 Read of size 4 at addr ffff888078070018 by task syz.5.273/7168 CPU: 0 UID: 0 PID: 7168 Comm: syz.5.273 Not tainted 6.14.0-syzkaller-13546-g16cd1c265776 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0x16e/0x5b0 mm/kasan/report.c:521 kasan_report+0x143/0x180 mm/kasan/report.c:634 ext4_ext_binsearch fs/ext4/extents.c:840 [inline] ext4_find_extent+0xb92/0xd80 fs/ext4/extents.c:955 ext4_ext_map_blocks+0x2e6/0x7d80 fs/ext4/extents.c:4205 ext4_map_create_blocks fs/ext4/inode.c:519 [inline] ext4_map_blocks+0x909/0x1a70 fs/ext4/inode.c:705 _ext4_get_block+0x23b/0x6b0 fs/ext4/inode.c:784 ext4_get_block_unwritten+0x2f/0x100 fs/ext4/inode.c:817 ext4_block_write_begin+0x4da/0x1520 fs/ext4/inode.c:1066 ext4_write_begin+0x786/0x1330 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x4aa/0xb20 fs/ext4/inode.c:2931 generic_perform_write+0x32b/0xa10 mm/filemap.c:4102 ext4_buffered_write_iter+0xc7/0x390 fs/ext4/file.c:299 ext4_file_write_iter+0x97f/0x1da0 fs/ext4/file.c:-1 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x711/0xd10 fs/read_write.c:684 ksys_write+0x19d/0x2d0 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f398418d169 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:00007f3984f9c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f39843a6160 RCX: 00007f398418d169 RDX: 000000000000fea7 RSI: 0000200000000200 RDI: 0000000000000009 RBP: 00007f398420e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f39843a6160 R15: 00007ffe171897d8 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x4bb pfn:0x78070 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000 raw: 00000000000004bb 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 7038, tgid 7036 (syz.4.251), ts 226581415281, free_ts 228936047594 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1717 prep_new_page mm/page_alloc.c:1725 [inline] get_page_from_freelist+0x352b/0x36c0 mm/page_alloc.c:3652 __alloc_frozen_pages_noprof+0x211/0x5b0 mm/page_alloc.c:4934 alloc_pages_mpol+0x339/0x690 mm/mempolicy.c:2301 folio_alloc_mpol_noprof+0x36/0x70 mm/mempolicy.c:2320 shmem_alloc_folio mm/shmem.c:1854 [inline] shmem_alloc_and_add_folio+0x490/0x1070 mm/shmem.c:1893 shmem_get_folio_gfp+0x655/0x1800 mm/shmem.c:2533 shmem_fault+0x223/0x5c0 mm/shmem.c:2734 __do_fault+0x137/0x390 mm/memory.c:5098 do_read_fault mm/memory.c:5518 [inline] do_fault mm/memory.c:5652 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault+0x3f0c/0x61c0 mm/memory.c:5997 __handle_mm_fault mm/memory.c:6140 [inline] handle_mm_fault+0x1129/0x1bf0 mm/memory.c:6309 faultin_page mm/gup.c:1193 [inline] __get_user_pages+0x1adc/0x4180 mm/gup.c:1491 populate_vma_page_range+0x266/0x340 mm/gup.c:1929 __mm_populate+0x27d/0x460 mm/gup.c:2032 mm_populate include/linux/mm.h:3470 [inline] vm_mmap_pgoff+0x390/0x530 mm/util.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 page last free pid 7043 tgid 7036 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1262 [inline] free_unref_folios+0xe0e/0x17f0 mm/page_alloc.c:2737 folios_put_refs+0x70a/0x800 mm/swap.c:992 folio_batch_release include/linux/pagevec.h:101 [inline] shmem_undo_range+0x595/0x1820 mm/shmem.c:1125 shmem_truncate_range mm/shmem.c:1237 [inline] shmem_evict_inode+0x29d/0xa80 mm/shmem.c:1365 evict+0x4fb/0x9b0 fs/inode.c:810 __dentry_kill+0x20d/0x630 fs/dcache.c:660 dput+0x19f/0x2b0 fs/dcache.c:902 __fput+0x60b/0x9f0 fs/file_table.c:473 task_work_run+0x253/0x310 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa11/0x27f0 kernel/exit.c:953 do_group_exit+0x207/0x2c0 kernel/exit.c:1102 get_signal+0x1696/0x1730 kernel/signal.c:3034 arch_do_signal_or_restart+0x98/0x840 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88807806ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88807806ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888078070000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888078070080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888078070100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================