================================================================== BUG: KASAN: use-after-free in leaf_paste_entries+0x441/0x1130 fs/reiserfs/lbalance.c:1362 Read of size 2 at addr ffff88804a882000 by task syz.1.747/7572 CPU: 1 PID: 7572 Comm: syz.1.747 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 print_address_description+0x60/0x2d0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xdf/0x130 mm/kasan/report.c:451 leaf_paste_entries+0x441/0x1130 fs/reiserfs/lbalance.c:1362 leaf_copy_dir_entries+0x62b/0x8f0 fs/reiserfs/lbalance.c:119 leaf_copy_boundary_item+0xb8c/0x2190 fs/reiserfs/lbalance.c:168 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline] leaf_move_items+0x85f/0xe00 fs/reiserfs/lbalance.c:726 leaf_shift_left+0xb9/0x450 fs/reiserfs/lbalance.c:750 balance_leaf_when_delete_left fs/reiserfs/do_balan.c:194 [inline] balance_leaf_when_delete fs/reiserfs/do_balan.c:272 [inline] balance_leaf+0x1321/0x10ec0 fs/reiserfs/do_balan.c:1393 do_balance+0x318/0x930 fs/reiserfs/do_balan.c:1888 reiserfs_cut_from_item+0x154d/0x1fa0 fs/reiserfs/stree.c:1838 reiserfs_do_truncate+0xa09/0x1390 fs/reiserfs/stree.c:1973 reiserfs_truncate_file+0x666/0xe40 fs/reiserfs/inode.c:2318 reiserfs_setattr+0xab3/0x1090 fs/reiserfs/inode.c:3409 notify_change+0xbcd/0xee0 fs/attr.c:505 do_truncate+0x1ac/0x240 fs/open.c:65 handle_truncate fs/namei.c:3273 [inline] do_open fs/namei.c:3620 [inline] path_openat+0x2922/0x2fa0 fs/namei.c:3750 do_filp_open+0x1e2/0x410 fs/namei.c:3777 do_sys_openat2+0x150/0x4b0 fs/open.c:1255 do_sys_open fs/open.c:1271 [inline] __do_sys_creat fs/open.c:1347 [inline] __se_sys_creat fs/open.c:1341 [inline] __x64_sys_creat+0x8c/0xb0 fs/open.c:1341 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f21a99cb799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f21a7c25028 EFLAGS: 00000246 ORIG_RAX: 0000000000000055 RAX: ffffffffffffffda RBX: 00007f21a9c44fa0 RCX: 00007f21a99cb799 RDX: 0000000000000000 RSI: 000000000000007b RDI: 0000200000000180 RBP: 00007f21a9a61c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f21a9c45038 R14: 00007f21a9c44fa0 R15: 00007ffe63570c08 The buggy address belongs to the page: page:ffffea00012a2080 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x100 pfn:0x4a882 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea00017a1088 ffffea0001169e08 0000000000000000 raw: 0000000000000100 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 0x1100cca(GFP_HIGHUSER_MOVABLE), pid 7467, ts 316636844966, free_ts 318154958581 prep_new_page mm/page_alloc.c:2426 [inline] get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501 alloc_pages_vma+0x393/0x7c0 mm/mempolicy.c:2146 shmem_alloc_page mm/shmem.c:1586 [inline] shmem_alloc_and_acct_page+0x47f/0xbe0 mm/shmem.c:1611 shmem_getpage_gfp+0x14f4/0x2d40 mm/shmem.c:1906 shmem_getpage mm/shmem.c:151 [inline] shmem_write_begin+0xcd/0x1a0 mm/shmem.c:2474 generic_perform_write+0x2b6/0x550 mm/filemap.c:3785 __generic_file_write_iter+0x25f/0x4e0 mm/filemap.c:3912 generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944 __kernel_write+0x51c/0x970 fs/read_write.c:539 __dump_emit+0x249/0x370 fs/coredump.c:943 dump_user_range+0x84/0x340 fs/coredump.c:1017 elf_core_dump+0x2fbd/0x3500 fs/binfmt_elf.c:2285 do_coredump+0x14c7/0x2ac0 fs/coredump.c:894 get_signal+0x40a/0x12c0 kernel/signal.c:2886 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1340 [inline] free_pcp_prepare mm/page_alloc.c:1391 [inline] free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317 free_unref_page_list+0x119/0x820 mm/page_alloc.c:3433 release_pages+0x186c/0x1be0 mm/swap.c:963 __pagevec_release+0x6d/0xe0 mm/swap.c:983 pagevec_release include/linux/pagevec.h:81 [inline] shmem_undo_range+0x62b/0x1930 mm/shmem.c:964 shmem_truncate_range mm/shmem.c:1063 [inline] shmem_evict_inode+0x220/0xa40 mm/shmem.c:1145 evict+0x4c9/0x8d0 fs/inode.c:647 __dentry_kill+0x431/0x650 fs/dcache.c:586 dentry_kill+0xb8/0x290 fs/dcache.c:-1 dput+0xd8/0x1a0 fs/dcache.c:893 __fput+0x5ee/0x930 fs/file_table.c:319 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x626/0x20c0 kernel/exit.c:883 do_group_exit+0x12e/0x300 kernel/exit.c:997 get_signal+0x6ca/0x12c0 kernel/signal.c:2900 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867 Memory state around the buggy address: ffff88804a881f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88804a881f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88804a882000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88804a882080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88804a882100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================