Re: [syzbot] [mm?] KASAN: use-after-free Read in copy_folio_from_iter_atomic (2)

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From: syzbot <syzbot+6cc93ec9a4035badb85f@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, mashiro.chen@mailbox.org,
	 syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [mm?] KASAN: use-after-free Read in copy_folio_from_iter_atomic (2)
Date: Sat, 25 Apr 2026 05:02:03 -0700	[thread overview]
Message-ID: <69ecad3b.a00a0220.1901e8.000f.GAE@google.com> (raw)
In-Reply-To: <20260425112428.81709-1-mashiro.chen@mailbox.org>

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in blk_update_request

==================================================================
BUG: KASAN: slab-use-after-free in __wake_up_common kernel/sched/wait.c:99 [inline]
BUG: KASAN: slab-use-after-free in __wake_up_common_lock+0x94/0x1e0 kernel/sched/wait.c:125
Read of size 8 at addr ffff8880402ce410 by task ksoftirqd/0/15

CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 __wake_up_common kernel/sched/wait.c:99 [inline]
 __wake_up_common_lock+0x94/0x1e0 kernel/sched/wait.c:125
 blk_update_request+0x57e/0xe60 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1178
 blk_complete_reqs block/blk-mq.c:1253 [inline]
 blk_done_softirq+0x10a/0x160 block/blk-mq.c:1258
 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622
 run_ksoftirqd+0x52/0x180 kernel/softirq.c:1076
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6698:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x3a6/0x690 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 open_inline_log fs/jfs/jfs_logmgr.c:1157 [inline]
 lmLogOpen+0x2d1/0xfa0 fs/jfs/jfs_logmgr.c:1067
 jfs_mount_rw+0xee/0x670 fs/jfs/jfs_mount.c:257
 jfs_fill_super+0x754/0xd80 fs/jfs/super.c:532
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6202:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kfree+0x1c5/0x6c0 mm/slub.c:6561
 lmLogClose+0x297/0x520 fs/jfs/jfs_logmgr.c:-1
 jfs_umount+0x2fb/0x3d0 fs/jfs/jfs_umount.c:124
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:646
 kill_block_super+0x44/0x90 fs/super.c:1725
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880402ce000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1040 bytes inside of
 freed 2048-byte region [ffff8880402ce000, ffff8880402ce800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880402c8000 pfn:0x402c8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000240(workingset|head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000240 ffff88801a010000 ffffea0000d48610 ffffea0000dfb010
raw: ffff8880402c8000 0000000800080005 00000000f5000000 0000000000000000
head: 0080000000000240 ffff88801a010000 ffffea0000d48610 ffffea0000dfb010
head: ffff8880402c8000 0000000800080005 00000000f5000000 0000000000000000
head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 67, tgid 67 (kworker/u8:4), ts 92180480282, free_ts 60062409081
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x33c/0x3d0 mm/slub.c:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0x530/0x7b0 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 neigh_alloc net/core/neighbour.c:521 [inline]
 ___neigh_create+0x722/0x2350 net/core/neighbour.c:655
 ip6_finish_output2+0x729/0x1430 net/ipv6/ip6_output.c:128
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip6_output+0x340/0x550 net/ipv6/ip6_output.c:246
 dst_output include/net/dst.h:470 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ndisc_send_skb+0xd0b/0x1670 net/ipv6/ndisc.c:512
 ndisc_send_ns+0xd7/0x160 net/ipv6/ndisc.c:671
 addrconf_dad_work+0xbea/0x1680 net/ipv6/addrconf.c:4294
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
page last free pid 5437 tgid 5437 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xfa6/0x10f0 mm/page_alloc.c:2943
 __slab_free+0x252/0x2a0 mm/slub.c:5608
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x33b/0x680 mm/slub.c:4905
 alloc_filename fs/namei.c:142 [inline]
 do_getname+0x2e/0x250 fs/namei.c:182
 getname include/linux/fs.h:2526 [inline]
 class_filename_constructor include/linux/fs.h:2553 [inline]
 do_sys_openat2+0xca/0x200 fs/open.c:1363
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880402ce300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880402ce380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880402ce400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8880402ce480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880402ce500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         27d128c1 Merge tag 'trace-ring-buffer-v7.1-3' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16ce22ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f2e8ebfec4636d32
dashboard link: https://syzkaller.appspot.com/bug?extid=6cc93ec9a4035badb85f
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16b1f702580000

next      parent reply	other threads:[~2026-04-25 12:02 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20260425112428.81709-1-mashiro.chen@mailbox.org>
2026-04-25 12:02 ` syzbot [this message]
     [not found] <20260424211614.47023-1-mashiro.chen@mailbox.org>
2026-04-24 21:23 ` [syzbot] [mm?] KASAN: use-after-free Read in copy_folio_from_iter_atomic (2) syzbot
     [not found] <20260423132557.28264-2-jakovnovak30@gmail.com>
2026-04-23 13:57 ` syzbot
     [not found] <CAAMO5pjxksZntoLX-6fCrsGFVE6Z+-goCM6xJ0pby-S5XKph+g@mail.gmail.com>
2026-04-20  4:18 ` syzbot
     [not found] <CAAMO5ph3W9SPGJEqB4A7ObR0G=2LdGNXLev1Y6rMRQDmN2e51Q@mail.gmail.com>
2026-04-20  4:18 ` syzbot
     [not found] <CAAMO5pgGENy_VO0b3uSEPpns6L_AZesZHW3fWv9=muqUFtKvyQ@mail.gmail.com>
2026-04-17 21:19 ` syzbot
2026-03-30  9:56 syzbot
2026-04-16 10:23 ` syzbot

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