loop3: detected capacity change from 0 to 1024 EXT4-fs (loop3): mounted filesystem without journal. Quota mode: none. ================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953 Read of size 4 at addr ffff8881336d4c0c by task syz.3.78/677 CPU: 1 PID: 677 Comm: syz.3.78 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106 print_address_description+0x71/0x200 mm/kasan/report.c:316 print_report+0x4a/0x60 mm/kasan/report.c:420 kasan_report+0x122/0x150 mm/kasan/report.c:524 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350 ext4_ext_binsearch fs/ext4/extents.c:837 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953 ext4_ext_map_blocks+0x1da/0x6080 fs/ext4/extents.c:4166 ext4_map_blocks+0x9cb/0x1b60 fs/ext4/inode.c:679 ext4_iomap_alloc fs/ext4/inode.c:3439 [inline] ext4_iomap_begin+0x72a/0xa90 fs/ext4/inode.c:3489 iomap_iter+0x5b7/0xb30 fs/iomap/iter.c:74 __iomap_dio_rw+0x1251/0x1bd0 fs/iomap/direct-io.c:607 iomap_dio_rw+0x41/0x90 fs/iomap/direct-io.c:696 ext4_dio_write_iter fs/ext4/file.c:557 [inline] ext4_file_write_iter+0xdbc/0x1440 fs/ext4/file.c:677 call_write_iter include/linux/fs.h:2282 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x5db/0xca0 fs/read_write.c:584 ksys_write+0x140/0x240 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:646 x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f767198f749 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:00007f767289f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f7671be5fa0 RCX: 00007f767198f749 RDX: 0000000000002400 RSI: 0000200000000000 RDI: 000000000000000b RBP: 00007f7671a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7671be6038 R14: 00007f7671be5fa0 R15: 00007ffed7cb1d88 The buggy address belongs to the physical page: page:ffffea0004cdb500 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1336d4 flags: 0x4000000000000000(zone=1) raw: 4000000000000000 ffffea0004cdb548 ffffea0004dc20c8 0000000000000000 raw: 0000000000000001 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 652, tgid 651 (syz.3.71), ts 45708435035, free_ts 46288916439 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650 get_page_from_freelist+0x2c7b/0x2cf0 mm/page_alloc.c:4554 __alloc_pages+0x1c3/0x450 mm/page_alloc.c:5868 __folio_alloc+0x12/0x40 mm/page_alloc.c:5900 __folio_alloc_node include/linux/gfp.h:245 [inline] folio_alloc include/linux/gfp.h:274 [inline] shmem_alloc_folio mm/shmem.c:1601 [inline] shmem_alloc_and_acct_folio+0x650/0x870 mm/shmem.c:1626 shmem_get_folio_gfp+0x119f/0x2230 mm/shmem.c:1955 shmem_fault+0x1ae/0x650 mm/shmem.c:2170 __do_fault mm/memory.c:4373 [inline] do_read_fault mm/memory.c:4739 [inline] do_fault+0x1a6f/0x1df0 mm/memory.c:4875 handle_pte_fault mm/memory.c:5171 [inline] __handle_mm_fault mm/memory.c:5313 [inline] handle_mm_fault+0x12fa/0x2640 mm/memory.c:5453 faultin_page mm/gup.c:1026 [inline] __get_user_pages+0x33d/0xd80 mm/gup.c:1250 populate_vma_page_range mm/gup.c:1607 [inline] __mm_populate+0x2e4/0x420 mm/gup.c:1721 mm_populate include/linux/mm.h:3148 [inline] vm_mmap_pgoff+0x268/0x3f0 mm/util.c:530 ksys_mmap_pgoff+0xf6/0x1d0 mm/mmap.c:1537 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline] __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86 x64_sys_call+0x8fd/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:10 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1551 [inline] free_pcp_prepare mm/page_alloc.c:1625 [inline] free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589 free_unref_page_list+0x112/0x8b0 mm/page_alloc.c:3740 release_pages+0xad1/0xb20 mm/swap.c:1048 __pagevec_release+0x71/0xe0 mm/swap.c:1068 pagevec_release include/linux/pagevec.h:71 [inline] folio_batch_release include/linux/pagevec.h:135 [inline] shmem_undo_range+0x51a/0x1470 mm/shmem.c:955 shmem_truncate_range mm/shmem.c:1071 [inline] shmem_evict_inode+0x242/0xa10 mm/shmem.c:1180 evict+0x493/0x890 fs/inode.c:708 iput_final fs/inode.c:1844 [inline] iput+0x620/0x670 fs/inode.c:1870 dentry_unlink_inode+0x33d/0x3f0 fs/dcache.c:405 __dentry_kill+0x460/0x670 fs/dcache.c:611 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x42/0x80 fs/dcache.c:918 __fput+0x5be/0x8f0 fs/file_table.c:328 ____fput+0x15/0x20 fs/file_table.c:348 task_work_run+0x1db/0x240 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xa25/0x2650 kernel/exit.c:886 Memory state around the buggy address: ffff8881336d4b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881336d4b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881336d4c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881336d4c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881336d4d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop3): ext4_ext_split:1080: inode #15: comm syz.3.78: p_ext > EXT_MAX_EXTENT!