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BUG: KASAN: out-of-bounds in leaf_paste_in_buffer+0x1c8/0xab0 fs/reiserfs/lbalance.c:1017
Read of size 18446744073709551229 at addr ffff88805c778000 by task syz.3.19/4356

CPU: 1 PID: 4356 Comm: syz.3.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x235/0x290 mm/kasan/generic.c:189
 memmove+0x25/0x60 mm/kasan/shadow.c:54
 leaf_paste_in_buffer+0x1c8/0xab0 fs/reiserfs/lbalance.c:1017
 balance_leaf_new_nodes_paste_whole fs/reiserfs/do_balan.c:1171 [inline]
 balance_leaf_new_nodes_paste fs/reiserfs/do_balan.c:1215 [inline]
 balance_leaf_new_nodes fs/reiserfs/do_balan.c:1246 [inline]
 balance_leaf+0x6682/0x10ec0 fs/reiserfs/do_balan.c:1450
 do_balance+0x318/0x930 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x6dd/0x810 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x1c3a/0x42a0 fs/reiserfs/inode.c:1077
 __block_write_begin_int+0x565/0x15d0 fs/buffer.c:2012
 reiserfs_write_begin+0x34b/0x810 fs/reiserfs/inode.c:2790
 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
 do_iter_readv_writev+0x47e/0x5f0 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x240/0x3a0 fs/read_write.c:1025
 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: 0033:0x7ff158c6a819
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:00007ff156ea3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007ff158ee4090 RCX: 00007ff158c6a819
RDX: 0000000000000001 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007ff158d00c91 R08: 000000000000000c R09: 0000000000000004
R10: 0000000000800fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff158ee4128 R14: 00007ff158ee4090 R15: 00007ffe4412c0e8
 </TASK>

The buggy address belongs to the page:
page:ffffea000171de00 refcount:1 mapcount:0 mapping:ffff88807bdf3b48 index:0x6ac pfn:0x5c778
memcg:ffff88807e3f0000
aops:shmem_aops ino:40d dentry name:"memfd:syzkaller"
flags: 0xfff0000008001e(referenced|uptodate|dirty|lru|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff0000008001e ffffea000171dd48 ffffea000171de48 ffff88807bdf3b48
raw: 00000000000006ac 0000000000000000 00000001ffffffff ffff88807e3f0000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100cca(GFP_HIGHUSER_MOVABLE), pid 4352, ts 69759316236, free_ts 66643389116
 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
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x745/0xd60 fs/read_write.c:594
 ksys_write+0x152/0x260 fs/read_write.c:647
 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
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
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x176/0x300 mm/mmu_gather.c:338
 unmap_region+0x344/0x3b0 mm/mmap.c:2669
 __do_munmap+0x9f8/0xdf0 mm/mmap.c:2899
 __vm_munmap+0x140/0x240 mm/mmap.c:2952
 __do_sys_munmap mm/mmap.c:2978 [inline]
 __se_sys_munmap mm/mmap.c:2974 [inline]
 __x64_sys_munmap+0x67/0x70 mm/mmap.c:2974
 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

Memory state around the buggy address:
 ffff88805c777f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805c777f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805c778000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff88805c778080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805c778100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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