On Fri, 28 Nov 2025 13:46:26 -0800 syzbot <[email protected]> wrote:
> syzbot has found a reproducer for the following issue on: > > HEAD commit: e538109ac71d Merge tag 'drm-fixes-2025-11-28' of https://g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10fd2112580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a1db0fea040c2a9f > dashboard link: https://syzkaller.appspot.com/bug?extid=6663075ddb9be85fa6e5 > compiler: Debian clang version 20.1.8 > (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12fd2112580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a10112580000 > > Downloadable assets: > disk image (non-bootable): > https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-e538109a.raw.xz > vmlinux: > https://storage.googleapis.com/syzbot-assets/3cf595fe0afc/vmlinux-e538109a.xz > kernel image: > https://storage.googleapis.com/syzbot-assets/e6e26f95e409/bzImage-e538109a.xz > mounted in repro: > https://storage.googleapis.com/syzbot-assets/445f48d13fdb/mount_7.gz > fsck result: failed (log: > https://syzkaller.appspot.com/x/fsck.log?x=11a10112580000) > > The issue was bisected to: > > commit 14152654805256d760315ec24e414363bfa19a06 > Author: Kent Overstreet <[email protected]> > Date: Mon Nov 25 05:21:27 2024 +0000 > > bcachefs: Bad btree roots are now autofix > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=108d43a8580000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=128d43a8580000 > console output: https://syzkaller.appspot.com/x/log.txt?x=148d43a8580000 Thanks. Bisection obviously went wrong. I'll cc the gfs2 list. > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: [email protected] > Fixes: 141526548052 ("bcachefs: Bad btree roots are now autofix") > > ================================================================== > BUG: KASAN: slab-use-after-free in > __list_del_entry_valid_or_report+0xb5/0x190 lib/list_debug.c:65 > Read of size 8 at addr ffff88800098a080 by task syz.0.17/5483 > > CPU: 0 UID: 0 PID: 5483 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS > 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 > 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 > __list_del_entry_valid_or_report+0xb5/0x190 lib/list_debug.c:65 > __list_del_entry_valid include/linux/list.h:132 [inline] > __list_del_entry include/linux/list.h:223 [inline] > list_del_init include/linux/list.h:295 [inline] > list_lru_del+0x98/0x210 mm/list_lru.c:210 > gfs2_quota_cleanup+0x21e/0x6f0 fs/gfs2/quota.c:1532 > gfs2_make_fs_ro+0x27a/0x300 fs/gfs2/super.c:566 > gfs2_put_super+0x224/0x950 fs/gfs2/super.c:598 > generic_shutdown_super+0x135/0x2c0 fs/super.c:642 > kill_block_super+0x44/0x90 fs/super.c:1729 > deactivate_locked_super+0xbc/0x130 fs/super.c:473 > cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318 > task_work_run+0x1d4/0x260 kernel/task_work.c:227 > exit_task_work include/linux/task_work.h:40 [inline] > do_exit+0x6b5/0x2300 kernel/exit.c:966 > do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 > __do_sys_exit_group kernel/exit.c:1118 [inline] > __se_sys_exit_group kernel/exit.c:1116 [inline] > __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116 > x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f4bb3d8f7c9 > Code: Unable to access opcode bytes at 0x7f4bb3d8f79f. > RSP: 002b:00007ffd56395328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4bb3d8f7c9 > RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000003 R08: 0000001d5639541f R09: 00007f4bb3fb4280 > R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f4bb3fb4280 R14: 0000000000000003 R15: 00007ffd563953e0 > </TASK> > > Allocated by task 5483: > kasan_save_stack mm/kasan/common.c:56 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 > unpoison_slab_object mm/kasan/common.c:342 [inline] > __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368 > kasan_slab_alloc include/linux/kasan.h:252 [inline] > slab_post_alloc_hook mm/slub.c:4978 [inline] > slab_alloc_node mm/slub.c:5288 [inline] > kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5295 > qd_alloc+0x50/0x250 fs/gfs2/quota.c:234 > gfs2_quota_init+0x762/0x1200 fs/gfs2/quota.c:1448 > gfs2_make_fs_rw+0x181/0x2b0 fs/gfs2/super.c:149 > gfs2_fill_super+0x1a7b/0x20d0 fs/gfs2/ops_fstype.c:1280 > get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1698 > gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1337 > vfs_get_tree+0x92/0x2b0 fs/super.c:1758 > fc_mount fs/namespace.c:1199 [inline] > do_new_mount_fc fs/namespace.c:3642 [inline] > do_new_mount+0x302/0xa10 fs/namespace.c:3718 > do_mount fs/namespace.c:4041 [inline] > __do_sys_mount fs/namespace.c:4229 [inline] > __se_sys_mount+0x313/0x410 fs/namespace.c:4206 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Freed by task 15: > kasan_save_stack mm/kasan/common.c:56 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 > __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 > kasan_save_free_info mm/kasan/kasan.h:406 [inline] > poison_slab_object mm/kasan/common.c:252 [inline] > __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 > kasan_slab_free include/linux/kasan.h:234 [inline] > slab_free_hook mm/slub.c:2543 [inline] > slab_free mm/slub.c:6642 [inline] > kmem_cache_free+0x19b/0x690 mm/slub.c:6752 > gfs2_qd_dealloc+0x70/0xe0 fs/gfs2/quota.c:111 > rcu_do_batch kernel/rcu/tree.c:2605 [inline] > rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861 > handle_softirqs+0x286/0x870 kernel/softirq.c:622 > run_ksoftirqd+0x9b/0x100 kernel/softirq.c:1063 > smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 > kthread+0x711/0x8a0 kernel/kthread.c:463 > ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > Last potentially related work creation: > kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56 > kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559 > __call_rcu_common kernel/rcu/tree.c:3123 [inline] > call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3243 > gfs2_quota_sync+0x3c4/0x460 fs/gfs2/quota.c:1361 > gfs2_sync_fs+0x4c/0xb0 fs/gfs2/super.c:658 > sync_filesystem+0xee/0x230 fs/sync.c:56 > generic_shutdown_super+0x6f/0x2c0 fs/super.c:621 > kill_block_super+0x44/0x90 fs/super.c:1729 > deactivate_locked_super+0xbc/0x130 fs/super.c:473 > cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318 > task_work_run+0x1d4/0x260 kernel/task_work.c:227 > exit_task_work include/linux/task_work.h:40 [inline] > do_exit+0x6b5/0x2300 kernel/exit.c:966 > do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 > __do_sys_exit_group kernel/exit.c:1118 [inline] > __se_sys_exit_group kernel/exit.c:1116 [inline] > __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116 > x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88800098a000 > which belongs to the cache gfs2_quotad of size 272 > The buggy address is located 128 bytes inside of > freed 272-byte region [ffff88800098a000, ffff88800098a110) > > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x98a > flags: 0x7ff00000000000(node=0|zone=0|lastcpupid=0x7ff) > page_type: f5(slab) > raw: 007ff00000000000 ffff888032687dc0 dead000000000122 0000000000000000 > raw: 0000000000000000 00000000800c000c 00000000f5000000 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Reclaimable, gfp_mask > 0x52c50(GFP_NOFS|__GFP_RECLAIMABLE|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), > pid 5483, tgid 5483 (syz.0.17), ts 105510017652, free_ts 102275632308 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x234/0x290 mm/page_alloc.c:1845 > prep_new_page mm/page_alloc.c:1853 [inline] > get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3879 > __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5178 > alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416 > alloc_slab_page mm/slub.c:3059 [inline] > allocate_slab+0x96/0x350 mm/slub.c:3232 > new_slab mm/slub.c:3286 [inline] > ___slab_alloc+0xf56/0x1990 mm/slub.c:4655 > __slab_alloc+0x65/0x100 mm/slub.c:4778 > __slab_alloc_node mm/slub.c:4854 [inline] > slab_alloc_node mm/slub.c:5276 [inline] > kmem_cache_alloc_noprof+0x3f9/0x6e0 mm/slub.c:5295 > qd_alloc+0x50/0x250 fs/gfs2/quota.c:234 > gfs2_quota_init+0x762/0x1200 fs/gfs2/quota.c:1448 > gfs2_make_fs_rw+0x181/0x2b0 fs/gfs2/super.c:149 > gfs2_fill_super+0x1a7b/0x20d0 fs/gfs2/ops_fstype.c:1280 > get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1698 > gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1337 > vfs_get_tree+0x92/0x2b0 fs/super.c:1758 > fc_mount fs/namespace.c:1199 [inline] > do_new_mount_fc fs/namespace.c:3642 [inline] > do_new_mount+0x302/0xa10 fs/namespace.c:3718 > page last free pid 5433 tgid 5433 stack trace: > reset_page_owner include/linux/page_owner.h:25 [inline] > free_pages_prepare mm/page_alloc.c:1394 [inline] > free_unref_folios+0xdb3/0x14f0 mm/page_alloc.c:2958 > folios_put_refs+0x584/0x670 mm/swap.c:1002 > free_pages_and_swap_cache+0x4be/0x520 mm/swap_state.c:358 > __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline] > tlb_batch_pages_flush mm/mmu_gather.c:149 [inline] > tlb_flush_mmu_free mm/mmu_gather.c:397 [inline] > tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404 > tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497 > exit_mmap+0x444/0xb40 mm/mmap.c:1293 > __mmput+0x118/0x430 kernel/fork.c:1133 > exit_mm+0x1da/0x2c0 kernel/exit.c:582 > do_exit+0x648/0x2300 kernel/exit.c:954 > do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 > __do_sys_exit_group kernel/exit.c:1118 [inline] > __se_sys_exit_group kernel/exit.c:1116 [inline] > __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116 > x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Memory state around the buggy address: > ffff888000989f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88800098a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >ffff88800098a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88800098a100: fb fb fc fc fc fc fc fc fc fc 00 00 00 00 00 00 > ffff88800098a180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ================================================================== > > > --- > 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.
