syzbot


KASAN: stack-out-of-bounds Write in filemap_get_entry

Status: upstream: reported on 2025/08/19 15:42
Subsystems: ntfs3
[Documentation on labels]
Reported-by: syzbot+3d4a7c1cd1446719a55a@syzkaller.appspotmail.com
First crash: 10d, last: 10d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ntfs3?] KASAN: stack-out-of-bounds Write in filemap_get_entry 0 (1) 2025/08/19 15:42

Sample crash report:
loop3: detected capacity change from 0 to 4096
==================================================================
BUG: KASAN: stack-out-of-bounds in filemap_get_entry+0xa1/0x2f0 mm/filemap.c:1865
Write of size 24 at addr ffffc9000c5e7740 by task syz.3.520/9784

CPU: 1 UID: 0 PID: 9784 Comm: syz.3.520 Tainted: G        W           6.17.0-rc1-syzkaller-00016-g8742b2d8935f #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G[  478.477403][ T9784] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memset+0x22/0x50 mm/kasan/shadow.c:84
 filemap_get_entry+0xa1/0x2f0 mm/filemap.c:1865
 __filemap_get_folio+0x37/0xa40 mm/filemap.c:1916
 filemap_get_folio include/linux/pagemap.h:794 [inline]
 do_read_cache_folio+0x9e/0x560 mm/filemap.c:3917
 do_read_cache_page mm/filemap.c:4023 [inline]
 read_cache_page+0x5d/0x170 mm/filemap.c:4032
 read_mapping_page include/linux/pagemap.h:985 [inline]
 inode_read_data+0xa7/0x480 fs/ntfs3/inode.c:1054
 ntfs_fill_super+0x39c8/0x40b0 fs/ntfs3/super.c:1533
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1692
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3805
 do_mount fs/namespace.c:4133 [inline]
 __do_sys_mount fs/namespace.c:4344 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4321
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f162654038a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f16247a5e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f16247a5ef0 RCX: 00007f162654038a
RDX: 0000200000000100 RSI: 0000200000000140 RDI: 00007f16247a5eb0
RBP: 0000200000000100 R08: 00007f16247a5ef0 R09: 0000000003800011
R10: 0000000003800011 R11: 0000000000000246 R12: 0000200000000140
R13: 00007f16247a5eb0 R14: 000000000001f7a0 R15: 00002000000001c0
 </TASK>

The buggy address belongs to stack of task syz.3.520/9784
 and is located at offset 64 in frame:
 filemap_get_entry+0x0/0x2f0 mm/filemap.c:-1

This frame has 1 object:
 [32, 88) 'xas'

The buggy address belongs to a 8-page vmalloc region starting at 0xffffc9000c5e0000 allocated at copy_process+0x545/0x3ae0 kernel/fork.c:2004
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x73bff
memcg:ffff888032963502
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888032963502
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 9781, tgid 9781 (syz.3.520), ts 478064035811, free_ts 478008644692
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x2119/0x21b0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xcf/0x1e0 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3642 [inline]
 __vmalloc_area_node mm/vmalloc.c:3720 [inline]
 __vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3893
 __vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3956
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:882
 copy_process+0x545/0x3ae0 kernel/fork.c:2004
 kernel_clone+0x224/0x7c0 kernel/fork.c:2605
 __do_sys_clone3 kernel/fork.c:2909 [inline]
 __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2888
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 1231 tgid 1231 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xb59/0xce0 mm/page_alloc.c:2895
 vfree+0x2ad/0x470 mm/vmalloc.c:3434
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3353
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffffc9000c5e7600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000c5e7680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000c5e7700: f1 f1 f1 f1 00 00 00 00 00 00 00 f3 f3 f3 f3 f3
                                                    ^
 ffffc9000c5e7780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000c5e7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/13 18:32 upstream 8742b2d8935f 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: stack-out-of-bounds Write in filemap_get_entry
* Struck through repros no longer work on HEAD.