syzbot


KASAN: slab-out-of-bounds Write in __schedule

Status: auto-obsoleted due to no activity on 2025/10/09 02:03
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+36ed63974f7313c022a9@syzkaller.appspotmail.com
First crash: 119d, last: 113d
Bug presence (2)
Date Name Commit Repro Result
2025/06/25 upstream (ToT) 7595b66ae9de syz [report] KASAN: out-of-bounds Write in end_buffer_read_sync
2025/09/30 upstream (ToT) 30d4efb2f5a5 syz Didn't crash
Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in __schedule (4) sctp 17 C error 4 781d 777d 0/29 auto-obsoleted due to no activity on 2023/12/10 17:35
linux-4.19 KASAN: use-after-free Read in __schedule 19 1 1695d 1695d 0/1 auto-closed as invalid on 2021/06/29 13:25
upstream KMSAN: uninit-value in __schedule (5) kernel 19 558 13d 560d 0/29 upstream: reported on 2024/04/10 09:12
linux-4.19 KASAN: use-after-free Read in __schedule (2) 19 1 1372d 1372d 0/1 auto-closed as invalid on 2022/05/18 22:28
android-54 BUG: unable to handle kernel paging request in __schedule 8 C 12 1700d 1856d 0/2 auto-obsoleted due to no activity on 2023/04/17 21:57
upstream KMSAN: uninit-value in __schedule (3) trace net 7 2 979d 982d 0/29 auto-obsoleted due to no activity on 2023/05/17 02:32
upstream KMSAN: uninit-value in __schedule (2) kernel 7 1 1152d 1152d 0/29 auto-obsoleted due to no activity on 2022/11/24 18:35
upstream WARNING: locking bug in __schedule mm 4 1943 211d 500d 0/29 auto-obsoleted due to no activity on 2025/06/02 23:27
upstream BUG: unable to handle kernel paging request in __schedule kernel 8 2 2878d 2873d 3/29 fixed on 2018/01/03 02:35

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in instrument_atomic_write include/linux/instrumented.h:87 [inline]
BUG: KASAN: slab-out-of-bounds in clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
BUG: KASAN: slab-out-of-bounds in clear_ti_thread_flag include/linux/thread_info.h:94 [inline]
BUG: KASAN: slab-out-of-bounds in clear_tsk_thread_flag include/linux/sched.h:2024 [inline]
BUG: KASAN: slab-out-of-bounds in clear_tsk_need_resched include/linux/sched.h:2055 [inline]
BUG: KASAN: slab-out-of-bounds in __schedule+0x72f/0x40d0 kernel/sched/core.c:6525
Write of size 8 at addr ffff888044c11dbf by task syz.2.1500/11494

CPU: 1 PID: 11494 Comm: syz.2.1500 Not tainted 6.1.142-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x220 mm/kasan/report.c:427
 kasan_report+0x10b/0x140 mm/kasan/report.c:531
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 instrument_atomic_write include/linux/instrumented.h:87 [inline]
 clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
 clear_ti_thread_flag include/linux/thread_info.h:94 [inline]
 clear_tsk_thread_flag include/linux/sched.h:2024 [inline]
 clear_tsk_need_resched include/linux/sched.h:2055 [inline]
 __schedule+0x72f/0x40d0 kernel/sched/core.c:6525
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:filemap_get_pages mm/filemap.c:2667 [inline]
RIP: 0010:filemap_read+0x602/0x2f80 mm/filemap.c:2759
Code: 00 00 00 48 8b bc 24 10 01 00 00 31 f6 e8 a6 5e 26 00 48 8d bc 24 c0 01 00 00 48 8b b4 24 30 01 00 00 e8 a1 f9 02 00 4c 89 f7 <4c> 89 ee 48 8b 94 24 90 00 00 00 48 8d 8c 24 20 02 00 00 e8 46 b4
RSP: 0018:ffffc900033e6920 EFLAGS: 00000286
RAX: 0000000000400040 RBX: 0000000000000000 RCX: 1ffff9200067ccfc
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88807837d598
RBP: ffffc900033e6c30 R08: dffffc0000000000 R09: ffffed100f06fabf
R10: ffffed100f06fabf R11: 1ffff1100f06fabe R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88807837d598 R15: 0000000000000000
 generic_file_read_iter+0x115/0x670 mm/filemap.c:2914
 __kernel_read+0x2dc/0x6b0 fs/read_write.c:428
 integrity_kernel_read+0x86/0xd0 security/integrity/iint.c:228
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
 ima_calc_file_hash+0x96b/0x17c0 security/integrity/ima/ima_crypto.c:573
 ima_collect_measurement+0x4b3/0xac0 security/integrity/ima/ima_api.c:293
 process_measurement+0xfae/0x1a10 security/integrity/ima/ima_main.c:351
 ima_file_check+0xc2/0x100 security/integrity/ima/ima_main.c:534
 do_open fs/namei.c:3628 [inline]
 path_openat+0x2679/0x2e70 fs/namei.c:3783
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
 do_sys_openat2+0x142/0x490 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1345
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe4ec98e929
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:00007fe4ec7ff038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe4ecbb6080 RCX: 00007fe4ec98e929
RDX: 0000000000143042 RSI: 00002000000000c0 RDI: ffffffffffffff9c
RBP: 00007fe4eca10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe4ecbb6080 R15: 00007ffc71b05948
 </TASK>

Allocated by task 2:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3398 [inline]
 kmem_cache_alloc_node+0x14d/0x320 mm/slub.c:3443
 alloc_task_struct_node kernel/fork.c:172 [inline]
 dup_task_struct+0x57/0x6b0 kernel/fork.c:981
 copy_process+0x5bd/0x4020 kernel/fork.c:2181
 kernel_clone+0x225/0x8b0 kernel/fork.c:2757
 kernel_thread+0xe5/0x140 kernel/fork.c:2817
 create_kthread kernel/kthread.c:399 [inline]
 kthreadd+0x536/0x6e0 kernel/kthread.c:748
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14b/0x970 kernel/rcu/tree.c:2845
 put_task_struct_rcu_user kernel/exit.c:231 [inline]
 release_task+0x14ad/0x1600 kernel/exit.c:281
 wait_task_zombie kernel/exit.c:1208 [inline]
 wait_consider_task+0x1978/0x2e40 kernel/exit.c:1435
 do_wait_thread kernel/exit.c:1498 [inline]
 do_wait+0x31c/0xb60 kernel/exit.c:1615
 kernel_wait4+0x1ab/0x270 kernel/exit.c:1778
 __do_sys_wait4 kernel/exit.c:1806 [inline]
 __se_sys_wait4 kernel/exit.c:1802 [inline]
 __x64_sys_wait4+0x130/0x1e0 kernel/exit.c:1802
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
 call_rcu+0x14b/0x970 kernel/rcu/tree.c:2845
 put_task_struct_rcu_user kernel/exit.c:231 [inline]
 release_task+0x14ad/0x1600 kernel/exit.c:281
 wait_task_zombie kernel/exit.c:1208 [inline]
 wait_consider_task+0x1978/0x2e40 kernel/exit.c:1435
 do_wait_thread kernel/exit.c:1498 [inline]
 do_wait+0x31c/0xb60 kernel/exit.c:1615
 kernel_wait4+0x1ab/0x270 kernel/exit.c:1778
 __do_sys_wait4 kernel/exit.c:1806 [inline]
 __se_sys_wait4 kernel/exit.c:1802 [inline]
 __x64_sys_wait4+0x130/0x1e0 kernel/exit.c:1802
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888044c10000
 which belongs to the cache task_struct of size 7360
The buggy address is located 255 bytes to the right of
 7360-byte region [ffff888044c10000, ffff888044c11cc0)

The buggy address belongs to the physical page:
page:ffffea0001130400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x44c10
head:ffffea0001130400 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff8880297b1f41
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888140008500
raw: 0000000000000000 0000000080040004 00000001ffffffff ffff8880297b1f41
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (init), ts 14388108998, free_ts 11242467742
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 alloc_slab_page+0x5d/0x160 mm/slub.c:1794
 allocate_slab mm/slub.c:1939 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1992
 ___slab_alloc+0xbc6/0x1220 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 kmem_cache_alloc_node+0x1e5/0x320 mm/slub.c:3443
 alloc_task_struct_node kernel/fork.c:172 [inline]
 dup_task_struct+0x57/0x6b0 kernel/fork.c:981
 copy_process+0x5bd/0x4020 kernel/fork.c:2181
 kernel_clone+0x225/0x8b0 kernel/fork.c:2757
 __ia32_sys_vfork+0xa9/0x100 kernel/fork.c:2860
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479
 free_contig_range+0x9d/0x150 mm/page_alloc.c:9574
 destroy_args+0xef/0x8bf mm/debug_vm_pgtable.c:1031
 debug_vm_pgtable+0x32a/0x37e mm/debug_vm_pgtable.c:1354
 do_one_initcall+0x214/0x7a0 init/main.c:1298
 do_initcall_level+0x137/0x1e4 init/main.c:1371
 do_initcalls+0x4b/0x8a init/main.c:1387
 kernel_init_freeable+0x3fa/0x5ac init/main.c:1626
 kernel_init+0x19/0x1b0 init/main.c:1514
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff888044c11c80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888044c11d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888044c11d80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
                                        ^
 ffff888044c11e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888044c11e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 48 8b             	add    %cl,-0x75(%rax)
   5:	bc 24 10 01 00       	mov    $0x11024,%esp
   a:	00 31                	add    %dh,(%rcx)
   c:	f6 e8                	imul   %al
   e:	a6                   	cmpsb  %es:(%rdi),%ds:(%rsi)
   f:	5e                   	pop    %rsi
  10:	26 00 48 8d          	es add %cl,-0x73(%rax)
  14:	bc 24 c0 01 00       	mov    $0x1c024,%esp
  19:	00 48 8b             	add    %cl,-0x75(%rax)
  1c:	b4 24                	mov    $0x24,%ah
  1e:	30 01                	xor    %al,(%rcx)
  20:	00 00                	add    %al,(%rax)
  22:	e8 a1 f9 02 00       	call   0x2f9c8
  27:	4c 89 f7             	mov    %r14,%rdi
* 2a:	4c 89 ee             	mov    %r13,%rsi <-- trapping instruction
  2d:	48 8b 94 24 90 00 00 	mov    0x90(%rsp),%rdx
  34:	00
  35:	48 8d 8c 24 20 02 00 	lea    0x220(%rsp),%rcx
  3c:	00
  3d:	e8                   	.byte 0xe8
  3e:	46                   	rex.RX
  3f:	b4                   	.byte 0xb4

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/01 01:50 linux-6.1.y 7e69c33e4858 6e83b42d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: slab-out-of-bounds Write in __schedule
2025/06/24 13:44 linux-6.1.y 58485ff1a74f e2f27c35 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: slab-out-of-bounds Write in __schedule
2025/07/01 02:02 linux-6.1.y 7e69c33e4858 6e83b42d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan BUG: unable to handle kernel paging request in __schedule
2025/06/24 15:07 linux-6.1.y 58485ff1a74f e2f27c35 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan BUG: unable to handle kernel paging request in __schedule
* Struck through repros no longer work on HEAD.