From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f77.google.com (mail-ot1-f77.google.com [209.85.210.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 555682AD10 for ; Thu, 9 Apr 2026 10:04:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.77 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775729074; cv=none; b=Y0rXOf423zG928/wrhiDZA8mXiseOjFPr0sa25gc+8DrpSDUInQB1L4WkedbWpUmuXfydz1qmKjhVwPMlreFg713p5VRzPmfq3kdfBSijwVM2osnasPgZ58ik0aZtQJjKZWbxQLLAaQTzjz8Qfifem6ev1DXi5eRJyfDO2Z3LfY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775729074; c=relaxed/simple; bh=0vp7hbRLcFGw0j36lHY9/NjMIx6QICcuxTWyXCNh2e0=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; 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006d021491bc7-68a62520f0cmr1331903eaf.24.1775729072292; Thu, 09 Apr 2026 03:04:32 -0700 (PDT) Date: Thu, 09 Apr 2026 03:04:32 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69d779b0.a00a0220.468cb.0018.GAE@google.com> Subject: [syzbot] [cgroups?] KASAN: slab-use-after-free Read in pressure_write From: syzbot To: cgroups@vger.kernel.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, mkoutny@suse.com, syzkaller-bugs@googlegroups.com, tj@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 591cd656a1bf Linux 7.0-rc7 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=114a36ba580000 kernel config: https://syzkaller.appspot.com/x/.config?x=45cb3c58fd963c27 dashboard link: https://syzkaller.appspot.com/bug?extid=33e571025d88efd1312c compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16cb33da580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12648bd6580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/87739bfd4864/disk-591cd656.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/56be68f80e4e/vmlinux-591cd656.xz kernel image: https://storage.googleapis.com/syzbot-assets/08638816d82a/bzImage-591cd656.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+33e571025d88efd1312c@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011 Read of size 8 at addr ffff88803160f208 by task syz.3.1283/9352 CPU: 0 UID: 0 PID: 9352 Comm: syz.3.1283 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011 cgroup_file_write+0x36f/0x790 kernel/cgroup/cgroup.c:4311 kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x629/0xba0 fs/read_write.c:688 ksys_write+0x156/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f73f541c819 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:00007f73f4a76028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f73f5695fa0 RCX: 00007f73f541c819 RDX: 000000000000002f RSI: 0000200000000080 RDI: 0000000000000004 RBP: 00007f73f54b2c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f73f5696038 R14: 00007f73f5695fa0 R15: 00007ffe5707b838 Allocated by task 9352: 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:5380 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] cgroup_file_open+0x90/0x3a0 kernel/cgroup/cgroup.c:4256 kernfs_fop_open+0x9eb/0xcb0 fs/kernfs/file.c:724 do_dentry_open+0x83d/0x13e0 fs/open.c:949 vfs_open+0x3b/0x350 fs/open.c:1081 do_open fs/namei.c:4677 [inline] path_openat+0x2e43/0x38a0 fs/namei.c:4836 do_file_open+0x23e/0x4a0 fs/namei.c:4865 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 9353: 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:2685 [inline] slab_free mm/slub.c:6165 [inline] kfree+0x1c1/0x6c0 mm/slub.c:6483 cgroup_file_release+0xd6/0x100 kernel/cgroup/cgroup.c:4283 kernfs_release_file fs/kernfs/file.c:764 [inline] kernfs_drain_open_files+0x392/0x720 fs/kernfs/file.c:834 kernfs_drain+0x470/0x600 fs/kernfs/dir.c:525 __kernfs_remove+0x3cf/0x660 fs/kernfs/dir.c:1513 kernfs_remove_by_name_ns+0xaf/0x130 fs/kernfs/dir.c:1722 kernfs_remove_by_name include/linux/kernfs.h:633 [inline] cgroup_rm_file kernel/cgroup/cgroup.c:1758 [inline] cgroup_addrm_files+0x684/0xc30 kernel/cgroup/cgroup.c:4483 cgroup_destroy_locked+0x321/0x630 kernel/cgroup/cgroup.c:6197 cgroup_rmdir+0x3e8/0x710 kernel/cgroup/cgroup.c:6311 kernfs_iop_rmdir+0x203/0x350 fs/kernfs/dir.c:1291 vfs_rmdir+0x400/0x6f0 fs/namei.c:5344 filename_rmdir+0x292/0x520 fs/namei.c:5399 __do_sys_rmdir fs/namei.c:5422 [inline] __se_sys_rmdir+0x2e/0x140 fs/namei.c:5419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88803160f200 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 8 bytes inside of freed 192-byte region [ffff88803160f200, ffff88803160f2c0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3160f flags: 0x80000000000000(node=0|zone=1) page_type: f5(slab) raw: 0080000000000000 ffff88813fe1a3c0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 17504889254, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x334/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x35c/0x710 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __kmalloc_cache_noprof+0x44e/0x690 mm/slub.c:5375 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] call_usermodehelper_setup+0x8e/0x270 kernel/umh.c:362 kobject_uevent_env+0x65b/0x9e0 lib/kobject_uevent.c:628 device_add+0x557/0xb80 drivers/base/core.c:3672 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2358 register_netdevice+0x12d7/0x1d10 net/core/dev.c:11441 register_netdev+0x40/0x60 net/core/dev.c:11557 nr_proto_init+0x14a/0x720 net/netrom/af_netrom.c:1424 do_one_initcall+0x250/0x8d0 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 page_owner free stack trace missing Memory state around the buggy address: ffff88803160f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88803160f180: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc >ffff88803160f200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88803160f280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88803160f300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup