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BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2596 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3a6a/0x4920 fs/ext4/extents.c:2934
Read of size 4 at addr ffff88811d3eec18 by task syz.3.3252/13791

CPU: 1 PID: 13791 Comm: syz.3.3252 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_rm_leaf fs/ext4/extents.c:2596 [inline]
 ext4_ext_remove_space+0x3a6a/0x4920 fs/ext4/extents.c:2934
 ext4_ext_truncate+0x169/0x1f0 fs/ext4/extents.c:4467
 ext4_truncate+0xaea/0x1290 fs/ext4/inode.c:4367
 ext4_evict_inode+0xf4f/0x1760 fs/ext4/inode.c:290
 evict+0x478/0x910 fs/inode.c:612
 iput_final fs/inode.c:1736 [inline]
 iput+0x638/0x7c0 fs/inode.c:1762
 dentry_unlink_inode+0x2cf/0x380 fs/dcache.c:378
 __dentry_kill+0x44f/0x650 fs/dcache.c:583
 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1
 dput+0x42/0x80 fs/dcache.c:883
 __fput+0x4fe/0x770 fs/file_table.c:294
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x127/0x190 kernel/task_work.c:189
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f6def879c29
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:00007ffe5ea344a8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00000000000ca87d RCX: 00007f6def879c29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f6defac2da0 R08: 0000000000000001 R09: 0000001e5ea3479f
R10: 0000001b2d120000 R11: 0000000000000246 R12: 00007f6defac0fac
R13: 00007f6defac0fa0 R14: ffffffffffffffff R15: 00007ffe5ea345c0

Allocated by task 95:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 user_path_at_empty+0x2f/0x50 fs/namei.c:2740
 do_readlinkat+0xd4/0x480 fs/stat.c:414
 __do_sys_readlink fs/stat.c:447 [inline]
 __se_sys_readlink fs/stat.c:444 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:444
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 95:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
 putname fs/namei.c:262 [inline]
 filename_lookup+0x459/0x600 fs/namei.c:2470
 user_path_at_empty+0x43/0x50 fs/namei.c:2740
 do_readlinkat+0xd4/0x480 fs/stat.c:414
 __do_sys_readlink fs/stat.c:447 [inline]
 __se_sys_readlink fs/stat.c:444 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:444
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff88811d3ee600
 which belongs to the cache names_cache of size 4096
The buggy address is located 1560 bytes inside of
 4096-byte region [ffff88811d3ee600, ffff88811d3ef600)
The buggy address belongs to the page:
page:ffffea000474fa00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d3e8
head:ffffea000474fa00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea000473a400 0000000200000002 ffff88810018a780
raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 10072, ts 799774021312, free_ts 799701385766
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2a6/0x450 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1af/0x2e0 mm/slub.c:2965
 getname_flags+0xb9/0x500 fs/namei.c:141
 user_path_at_empty+0x2f/0x50 fs/namei.c:2740
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0xff/0x520 fs/stat.c:193
 vfs_fstatat fs/stat.c:215 [inline]
 __do_sys_newfstatat fs/stat.c:383 [inline]
 __se_sys_newfstatat+0xc6/0x340 fs/stat.c:377
 __x64_sys_newfstatat+0x9b/0xb0 fs/stat.c:377
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 __free_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5431 [inline]
 __free_pages+0xdd/0x380 mm/page_alloc.c:5440
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x15f/0x190 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x111/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc+0x183/0x330 mm/slub.c:4034
 kmalloc include/linux/slab.h:557 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 ops_init+0x89/0x4a0 net/core/net_namespace.c:134
 setup_net+0x36d/0xb50 net/core/net_namespace.c:345
 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486

Memory state around the buggy address:
 ffff88811d3eeb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d3eeb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811d3eec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88811d3eec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d3eed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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