================================================================== 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 ffff888123fa4c94 by task kworker/u4:1/10 CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: writeback wb_workfn (flush-7:2) 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+0x1dc/0x6060 fs/ext4/extents.c:4166 ext4_map_blocks+0x9cb/0x1b60 fs/ext4/inode.c:679 mpage_map_one_extent fs/ext4/inode.c:2435 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2488 [inline] ext4_writepages+0x1260/0x3020 fs/ext4/inode.c:2856 do_writepages+0x3a9/0x5e0 mm/page-writeback.c:2494 __writeback_single_inode+0xc6/0xad0 fs/fs-writeback.c:1612 writeback_sb_inodes+0x9b8/0x1550 fs/fs-writeback.c:1903 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2079 wb_do_writeback fs/fs-writeback.c:2226 [inline] wb_workfn+0x350/0xda0 fs/fs-writeback.c:2266 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2449 kthread+0x281/0x320 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Allocated by task 297: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:333 kasan_slab_alloc include/linux/kasan.h:202 [inline] slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768 slab_alloc_node mm/slub.c:3382 [inline] slab_alloc mm/slub.c:3392 [inline] __kmem_cache_alloc_lru mm/slub.c:3399 [inline] kmem_cache_alloc_lru+0x104/0x280 mm/slub.c:3415 alloc_inode_sb include/linux/fs.h:3263 [inline] shmem_alloc_inode+0x28/0x40 mm/shmem.c:3913 alloc_inode fs/inode.c:264 [inline] new_inode_pseudo+0x70/0x1f0 fs/inode.c:1073 new_inode+0x28/0x1e0 fs/inode.c:1101 shmem_get_inode+0x349/0xc20 mm/shmem.c:2368 shmem_symlink+0x9e/0x4c0 mm/shmem.c:3165 vfs_symlink+0x261/0x3f0 fs/namei.c:4470 do_symlinkat+0x124/0x5a0 fs/namei.c:4499 __do_sys_symlink fs/namei.c:4521 [inline] __se_sys_symlink fs/namei.c:4519 [inline] __x64_sys_symlink+0x7e/0x90 fs/namei.c:4519 x64_sys_call+0x369/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:89 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 Freed by task 344: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:241 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:249 kasan_slab_free include/linux/kasan.h:178 [inline] slab_free_hook mm/slub.c:1750 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776 slab_free mm/slub.c:3712 [inline] kmem_cache_free+0x12d/0x300 mm/slub.c:3737 shmem_free_in_core_inode+0x90/0xb0 mm/shmem.c:3923 i_callback+0x5a/0x80 fs/inode.c:253 rcu_do_batch+0x515/0xb90 kernel/rcu/tree.c:2297 rcu_core+0x5a5/0xe70 kernel/rcu/tree.c:2557 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642 __do_softirq+0xb/0xd kernel/softirq.c:680 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496 __call_rcu_common kernel/rcu/tree.c:2807 [inline] call_rcu+0xd4/0xf90 kernel/rcu/tree.c:2926 destroy_inode fs/inode.c:319 [inline] evict+0x7f6/0x890 fs/inode.c:723 iput_final fs/inode.c:1844 [inline] iput+0x620/0x670 fs/inode.c:1870 do_unlinkat+0x375/0x6b0 fs/namei.c:4396 __do_sys_unlink fs/namei.c:4437 [inline] __se_sys_unlink fs/namei.c:4435 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4435 x64_sys_call+0x958/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:88 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 The buggy address belongs to the object at ffff888123fa4b58 which belongs to the cache shmem_inode_cache of size 840 The buggy address is located 316 bytes inside of 840-byte region [ffff888123fa4b58, ffff888123fa4ea0) The buggy address belongs to the physical page: page:ffffea00048fe900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x123fa4 head:ffffea00048fe900 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000122 ffff8881001ecd80 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 349, tgid 349 (syz-executor), ts 27769171127, free_ts 27327814755 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 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1967 [inline] new_slab+0x98/0x3d0 mm/slub.c:2020 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177 __slab_alloc+0x5e/0xa0 mm/slub.c:3263 slab_alloc_node mm/slub.c:3348 [inline] slab_alloc mm/slub.c:3392 [inline] __kmem_cache_alloc_lru mm/slub.c:3399 [inline] kmem_cache_alloc_lru+0x144/0x280 mm/slub.c:3415 alloc_inode_sb include/linux/fs.h:3263 [inline] shmem_alloc_inode+0x28/0x40 mm/shmem.c:3913 alloc_inode fs/inode.c:264 [inline] new_inode_pseudo+0x70/0x1f0 fs/inode.c:1073 new_inode+0x28/0x1e0 fs/inode.c:1101 shmem_get_inode+0x349/0xc20 mm/shmem.c:2368 shmem_symlink+0x9e/0x4c0 mm/shmem.c:3165 vfs_symlink+0x261/0x3f0 fs/namei.c:4470 do_symlinkat+0x124/0x5a0 fs/namei.c:4499 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+0x8f/0x530 mm/page_alloc.c:3687 free_the_page mm/page_alloc.c:836 [inline] __free_pages+0x67/0x100 mm/page_alloc.c:5957 __vunmap+0x9af/0xb70 mm/vmalloc.c:2739 __vfree mm/vmalloc.c:2788 [inline] vfree+0x61/0x90 mm/vmalloc.c:2819 kcov_put kernel/kcov.c:437 [inline] kcov_close+0x2b/0x50 kernel/kcov.c:533 __fput+0x1fc/0x8f0 fs/file_table.c:320 ____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 do_group_exit+0x210/0x2d0 kernel/exit.c:1028 get_signal+0x13b5/0x1520 kernel/signal.c:2889 arch_do_signal_or_restart+0xb0/0x1030 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303 Memory state around the buggy address: ffff888123fa4b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888123fa4c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888123fa4c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888123fa4d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888123fa4d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================