From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-io1-f78.google.com (mail-io1-f78.google.com [209.85.166.78]) (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 B09BE1F956 for ; Sat, 19 Jul 2025 16:58:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752944320; cv=none; b=VINW+Fvf9WG+HdDlGybG8WWWtUSh5CjSkKgJAJCamHsbPT06r1uTYWmSqjqd2EYr0MaGWwfKEsgJfWtA0ADUWOxkW47QOLWNxJsuuwOvJQNKCiMxgWMmOTPEprm8Y3Q4FNpRyWehAjCFbERna2LAgWbOUh7kePNsE0hkVfzvO0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752944320; c=relaxed/simple; bh=9Gq+leZb/A+D6ye3VY2Hb0yCgnTy75wf619P/wTOCpU=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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linux-bcachefs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a5e:8c06:0:b0:864:4b3a:9e3a with SMTP id ca18e2360f4ac-879c298bce6mr1503078339f.13.1752944314711; Sat, 19 Jul 2025 09:58:34 -0700 (PDT) Date: Sat, 19 Jul 2025 09:58:34 -0700 In-Reply-To: <687a71bf.a70a0220.693ce.006b.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <687bceba.a70a0220.693ce.008d.GAE@google.com> Subject: Re: [syzbot] [bcachefs?] KASAN: slab-use-after-free Write in bch2_get_next_dev From: syzbot To: kent.overstreet@linux.dev, linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: d086c886ceb9 Add linux-next specific files for 20250718 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=17bd438c580000 kernel config: https://syzkaller.appspot.com/x/.config?x=cc0cd9fdf69889c3 dashboard link: https://syzkaller.appspot.com/bug?extid=2b98caf09c41174a9697 compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1480c38c580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=112df8f0580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/4435f80a19c4/disk-d086c886.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/9a7dc57a5ea3/vmlinux-d086c886.xz kernel image: https://storage.googleapis.com/syzbot-assets/da9f2dc22ae1/bzImage-d086c886.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/30708d56eaf8/mount_2.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+2b98caf09c41174a9697@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline] BUG: KASAN: slab-use-after-free in atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline] BUG: KASAN: slab-use-after-free in bch2_dev_get fs/bcachefs/sb-members.h:114 [inline] BUG: KASAN: slab-use-after-free in bch2_get_next_dev+0x38f/0x4e0 fs/bcachefs/sb-members.h:145 Write of size 8 at addr ffff88807b3cc040 by task kworker/u9:4/5922 CPU: 0 UID: 0 PID: 5922 Comm: kworker/u9:4 Not tainted 6.16.0-rc6-next-20250718-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: bcachefs_journal journal_write_done Call Trace: 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 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline] bch2_dev_get fs/bcachefs/sb-members.h:114 [inline] bch2_get_next_dev+0x38f/0x4e0 fs/bcachefs/sb-members.h:145 bch2_do_discards+0x20/0x160 fs/bcachefs/alloc_background.c:1935 journal_write_done+0x11b9/0x13f0 fs/bcachefs/journal_io.c:1822 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 5859: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4396 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] __bch2_dev_alloc+0xa7/0xc30 fs/bcachefs/super.c:1487 bch2_dev_alloc+0xcd/0x180 fs/bcachefs/super.c:1558 bch2_fs_alloc fs/bcachefs/super.c:1068 [inline] bch2_fs_open+0x256f/0x2760 fs/bcachefs/super.c:2395 bch2_fs_get_tree+0x44f/0x1540 fs/bcachefs/fs.c:2440 vfs_get_tree+0x92/0x2b0 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 Freed by task 5859: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kfree+0x18e/0x440 mm/slub.c:4879 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x22b/0x480 lib/kobject.c:737 bch2_fs_free+0x4b3/0x5c0 fs/bcachefs/super.c:749 bch2_fs_get_tree+0xb76/0x1540 fs/bcachefs/fs.c:2572 vfs_get_tree+0x92/0x2b0 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 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548 insert_work+0x3d/0x330 kernel/workqueue.c:2184 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2339 queue_work_on+0x181/0x270 kernel/workqueue.c:2390 queue_work include/linux/workqueue.h:669 [inline] bch2_dev_do_discards fs/bcachefs/alloc_background.c:1925 [inline] bch2_do_discards+0xd0/0x160 fs/bcachefs/alloc_background.c:1936 journal_write_done+0x11b9/0x13f0 fs/bcachefs/journal_io.c:1822 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Second to last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548 insert_work+0x3d/0x330 kernel/workqueue.c:2184 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2339 queue_work_on+0x181/0x270 kernel/workqueue.c:2390 queue_work include/linux/workqueue.h:669 [inline] bch2_dev_do_discards fs/bcachefs/alloc_background.c:1925 [inline] bch2_do_discards+0xd0/0x160 fs/bcachefs/alloc_background.c:1936 journal_write_done+0x11b9/0x13f0 fs/bcachefs/journal_io.c:1822 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff88807b3cc000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 64 bytes inside of freed 4096-byte region [ffff88807b3cc000, ffff88807b3cd000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b3c8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801a442140 ffffea0000cdf200 dead000000000002 raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801a442140 ffffea0000cdf200 dead000000000002 head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0001ecf201 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5228, tgid 5228 (udevadm), ts 37270032838, free_ts 31080557231 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+0x21e4/0x22c0 mm/page_alloc.c:3858 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 alloc_slab_page mm/slub.c:2487 [inline] allocate_slab+0x8a/0x370 mm/slub.c:2655 new_slab mm/slub.c:2709 [inline] ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891 __slab_alloc mm/slub.c:3981 [inline] __slab_alloc_node mm/slub.c:4056 [inline] slab_alloc_node mm/slub.c:4217 [inline] __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4391 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1039 [inline] kernfs_iop_get_link+0x66/0x6c0 fs/kernfs/symlink.c:137 vfs_readlink+0x24d/0x550 fs/namei.c:5375 do_readlinkat+0x215/0x500 fs/stat.c:590 __do_sys_readlink fs/stat.c:613 [inline] __se_sys_readlink fs/stat.c:610 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:610 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 1 tgid 1 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895 __free_pages mm/page_alloc.c:5260 [inline] free_contig_range+0x1bd/0x4a0 mm/page_alloc.c:7117 destroy_args+0x7e/0x5d0 mm/debug_vm_pgtable.c:958 debug_vm_pgtable+0x404/0x420 mm/debug_vm_pgtable.c:1340 do_one_initcall+0x233/0x820 init/main.c:1269 do_initcall_level+0x137/0x1f0 init/main.c:1331 do_initcalls+0x69/0xd0 init/main.c:1347 kernel_init_freeable+0x3d9/0x590 init/main.c:1579 kernel_init+0x1d/0x1d0 init/main.c:1469 ret_from_fork+0x3f9/0x770 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: ffff88807b3cbf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88807b3cbf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88807b3cc000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807b3cc080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807b3cc100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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.