==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x694/0xa40 fs/reiserfs/lbalance.c:1037
Write of size 4048 at addr ffff0000f91a6030 by task syz.3.705/6872

CPU: 1 PID: 6872 Comm: syz.3.705 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x258/0x290 mm/kasan/generic.c:189
 memcpy+0x60/0x90 mm/kasan/shadow.c:66
 leaf_paste_in_buffer+0x694/0xa40 fs/reiserfs/lbalance.c:1037
 balance_leaf_paste_left_whole fs/reiserfs/do_balan.c:564 [inline]
 balance_leaf_paste_left fs/reiserfs/do_balan.c:594 [inline]
 balance_leaf_left fs/reiserfs/do_balan.c:613 [inline]
 balance_leaf+0x450c/0xdee0 fs/reiserfs/do_balan.c:1409
 do_balance+0x270/0x794 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x640/0x6e8 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x1538/0x3860 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x3d8/0x13c0 fs/buffer.c:1991
 __block_write_begin+0x7c/0xa0 fs/buffer.c:2041
 reiserfs_write_begin+0x328/0x718 fs/reiserfs/inode.c:2775
 generic_cont_expand_simple+0x130/0x208 fs/buffer.c:2347
 reiserfs_setattr+0x540/0x1014 fs/reiserfs/inode.c:3305
 notify_change+0xb5c/0xe20 fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 do_sys_ftruncate+0x284/0x318 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __arm64_sys_ftruncate+0x60/0x74 fs/open.c:202
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the physical page:
page:00000000190bd62a refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1391a6
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f91a5f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f91a5f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000f91a6000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                     ^
 ffff0000f91a6080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f91a6100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
REISERFS panic (device loop3): vs-12195 balance_leaf: CFR not initialized
------------[ cut here ]------------
kernel BUG at fs/reiserfs/prints.c:390!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 6872 Comm: syz.3.705 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __reiserfs_panic+0x150/0x154 fs/reiserfs/prints.c:384
lr : __reiserfs_panic+0x150/0x154 fs/reiserfs/prints.c:384
sp : ffff800021ac64a0
x29: ffff800021ac6540 x28: ffff700004358cd4 x27: dfff800000000000
x26: ffff800021ac6f68 x25: ffff0000d2f70000 x24: ffff700004358c98
x23: ffff800021ac64c0 x22: ffff800011e1fc40 x21: ffff0000d1216000
x20: ffff800011e1fc20 x19: ffff800014a54c7c x18: 1fffe00033e6db7e
x17: ffff8000153bd000 x16: ffff800011bb65f8 x15: 0000000040000000
x14: 0000000000000001 x13: 1fffe00033e6dba3 x12: 0000000000000000
x11: ff008000083154bc x10: 0000000000000000 x9 : 328521218fa4b800
x8 : 328521218fa4b800 x7 : ffff800011d1c160 x6 : ffff80000825ab20
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff800008541118
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000049
Call trace:
 __reiserfs_panic+0x150/0x154 fs/reiserfs/prints.c:384
 balance_leaf+0xa6fc/0xdee0 fs/reiserfs/do_balan.c:1439
 do_balance+0x270/0x794 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x640/0x6e8 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x1538/0x3860 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x3d8/0x13c0 fs/buffer.c:1991
 __block_write_begin+0x7c/0xa0 fs/buffer.c:2041
 reiserfs_write_begin+0x328/0x718 fs/reiserfs/inode.c:2775
 generic_cont_expand_simple+0x130/0x208 fs/buffer.c:2347
 reiserfs_setattr+0x540/0x1014 fs/reiserfs/inode.c:3305
 notify_change+0xb5c/0xe20 fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 do_sys_ftruncate+0x284/0x318 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __arm64_sys_ftruncate+0x60/0x74 fs/open.c:202
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 912f00a5 911aa2a1 aa1303e4 97ffe2b2 (d4210000) 
---[ end trace 0000000000000000 ]---