On Mon, Dec 9, 2024 at 12:00 AM Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote: > > > > On 2024/12/9 14:25, Qi Zheng wrote: > > > > > > On 2024/12/8 01:14, syzbot wrote: > >> Hello, > >> > >> syzbot found the following issue on: > >> > >> HEAD commit: af2ea8ab7a54 Add linux-next specific files for 20241205 > >> git tree: linux-next > >> console output: https://syzkaller.appspot.com/x/log.txt?x=13c4e8df980000 > >> kernel config: > >> https://syzkaller.appspot.com/x/.config?x=76f158395f6f15fd > >> dashboard link: > >> https://syzkaller.appspot.com/bug?extid=1c58afed1cfd2f57efee > >> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for > >> Debian) 2.40 > >> syz repro: > >> https://syzkaller.appspot.com/x/repro.syz?x=133850f8580000 > >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17be9330580000 > >> > >> Downloadable assets: > >> disk image: > >> https://storage.googleapis.com/syzbot-assets/8af0861258fa/disk-af2ea8ab.raw.xz > >> vmlinux: > >> https://storage.googleapis.com/syzbot-assets/ffb38cf7a344/vmlinux-af2ea8ab.xz > >> kernel image: > >> https://storage.googleapis.com/syzbot-assets/6fbd2e50358a/bzImage-af2ea8ab.xz > >> > >> The issue was bisected to: > >> > >> commit 5b29c4156f5801fced2ec504b44ab98f60c480bf > >> Author: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> > >> Date: Wed Dec 4 11:09:51 2024 +0000 > >> > >> x86: select ARCH_SUPPORTS_PT_RECLAIM if X86_64 > >> > >> bisection log: > >> https://syzkaller.appspot.com/x/bisect.txt?x=16d344df980000 > >> final oops: > >> https://syzkaller.appspot.com/x/report.txt?x=15d344df980000 > >> console output: https://syzkaller.appspot.com/x/log.txt?x=11d344df980000 > >> > >> IMPORTANT: if you fix the issue, please add the following tag to the > >> commit: > >> Reported-by: syzbot+1c58afed1cfd2f57efee@xxxxxxxxxxxxxxxxxxxxxxxxx > >> Fixes: 5b29c4156f58 ("x86: select ARCH_SUPPORTS_PT_RECLAIM if X86_64") > >> > >> ================================================================== > >> BUG: KASAN: slab-use-after-free in __lock_acquire+0x78/0x2100 > >> kernel/locking/lockdep.c:5089 > >> Read of size 8 at addr ffff888034718978 by task syz-executor352/6070 > >> > >> CPU: 0 UID: 0 PID: 6070 Comm: syz-executor352 Not tainted > >> 6.13.0-rc1-next-20241205-syzkaller #0 > >> Hardware name: Google Google Compute Engine/Google Compute Engine, > >> BIOS Google 09/13/2024 > >> Call Trace: > >> <TASK> > >> __dump_stack lib/dump_stack.c:94 [inline] > >> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > >> print_address_description mm/kasan/report.c:378 [inline] > >> print_report+0x169/0x550 mm/kasan/report.c:489 > >> kasan_report+0x143/0x180 mm/kasan/report.c:602 > >> __lock_acquire+0x78/0x2100 kernel/locking/lockdep.c:5089 > >> lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > >> __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] > >> _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 > >> spin_lock include/linux/spinlock.h:351 [inline] > >> move_pages_pte+0x8aa/0x3400 mm/userfaultfd.c:1248 > >> move_pages+0xe75/0x16a0 mm/userfaultfd.c:1754 > >> userfaultfd_move fs/userfaultfd.c:1899 [inline] > >> userfaultfd_ioctl+0x5221/0x6840 fs/userfaultfd.c:2022 > >> vfs_ioctl fs/ioctl.c:51 [inline] > >> __do_sys_ioctl fs/ioctl.c:906 [inline] > >> __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 > >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] > >> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > >> entry_SYSCALL_64_after_hwframe+0x77/0x7f > >> RIP: 0033:0x7fed8de85af9 > >> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 > >> RSP: 002b:00007fed8de40238 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > >> RAX: ffffffffffffffda RBX: 00007fed8df10328 RCX: 00007fed8de85af9 > >> RDX: 0000000020000080 RSI: 00000000c028aa05 RDI: 0000000000000003 > >> RBP: 00007fed8df10320 R08: 00007fed8de406c0 R09: 00007fed8de406c0 > >> R10: 00007fed8de406c0 R11: 0000000000000246 R12: 00007fed8dedd334 > >> R13: 0000000000000010 R14: 00007ffc241241e0 R15: 00007ffc241242c8 > >> </TASK> > >> > >> Allocated by task 6070: > >> kasan_save_stack mm/kasan/common.c:47 [inline] > >> kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 > >> unpoison_slab_object mm/kasan/common.c:319 [inline] > >> __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345 > >> kasan_slab_alloc include/linux/kasan.h:250 [inline] > >> slab_post_alloc_hook mm/slub.c:4104 [inline] > >> slab_alloc_node mm/slub.c:4153 [inline] > >> kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4160 > >> ptlock_alloc+0x20/0x70 mm/memory.c:7026 > >> ptlock_init include/linux/mm.h:2971 [inline] > >> pagetable_pte_ctor include/linux/mm.h:2998 [inline] > >> __pte_alloc_one_noprof include/asm-generic/pgalloc.h:73 [inline] > >> pte_alloc_one+0xd3/0x510 arch/x86/mm/pgtable.c:41 > >> __do_huge_pmd_anonymous_page mm/huge_memory.c:1229 [inline] > >> do_huge_pmd_anonymous_page+0x2fb/0xb30 mm/huge_memory.c:1374 > >> create_huge_pmd mm/memory.c:5737 [inline] > >> __handle_mm_fault mm/memory.c:5986 [inline] > >> handle_mm_fault+0x15a7/0x1bb0 mm/memory.c:6183 > >> do_user_addr_fault arch/x86/mm/fault.c:1338 [inline] > >> handle_page_fault arch/x86/mm/fault.c:1481 [inline] > >> exc_page_fault+0x459/0x8b0 arch/x86/mm/fault.c:1539 > >> asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 > >> > >> Freed by task 6071: > >> kasan_save_stack mm/kasan/common.c:47 [inline] > >> kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 > >> kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576 > >> poison_slab_object mm/kasan/common.c:247 [inline] > >> __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 > >> kasan_slab_free include/linux/kasan.h:233 [inline] > >> slab_free_hook mm/slub.c:2338 [inline] > >> slab_free mm/slub.c:4598 [inline] > >> kmem_cache_free+0x195/0x410 mm/slub.c:4700 > >> pagetable_pte_dtor include/linux/mm.h:3009 [inline] > > > > OK, so the problem is that ptdesc->ptl is not freed via RCU: > > > > ___pte_free_tlb > > --> pagetable_pte_dtor > > --> ptlock_free > > --> kmem_cache_free (free immediately!) > > paravirt_tlb_remove_table > > --> free PTE page via RCU > > > > In retract_page_tables(), it calls pte_free_defer() to free > > ptdesc->ptl and PTE page via RCU, so there is no problem. > > > > To fix it, will also free ptdesc->ptl in ptlock_free() via RCU. > > > >> ___pte_free_tlb+0x2b/0x140 arch/x86/mm/pgtable.c:63 > >> __pte_free_tlb arch/x86/include/asm/pgalloc.h:61 [inline] > >> free_pte+0x142/0x190 mm/pt_reclaim.c:31 > >> zap_pte_range mm/memory.c:1780 [inline] > >> zap_pmd_range mm/memory.c:1822 [inline] > >> zap_pud_range mm/memory.c:1851 [inline] > >> zap_p4d_range mm/memory.c:1872 [inline] > >> unmap_page_range+0x4062/0x48d0 mm/memory.c:1893 > >> zap_page_range_single+0x45c/0x630 mm/memory.c:2018 > >> madvise_dontneed_single_vma mm/madvise.c:859 [inline] > >> madvise_dontneed_free mm/madvise.c:940 [inline] > >> madvise_vma_behavior mm/madvise.c:1270 [inline] > >> madvise_walk_vmas mm/madvise.c:1502 [inline] > >> do_madvise+0x2774/0x4d90 mm/madvise.c:1689 > >> __do_sys_madvise mm/madvise.c:1705 [inline] > >> __se_sys_madvise mm/madvise.c:1703 [inline] > >> __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:1703 > >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] > >> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > >> entry_SYSCALL_64_after_hwframe+0x77/0x7f > >> > >> The buggy address belongs to the object at ffff888034718960 > >> which belongs to the cache page->ptl of size 64 > >> The buggy address is located 24 bytes inside of > >> freed 64-byte region [ffff888034718960, ffff8880347189a0) > >> > >> The buggy address belongs to the physical page: > >> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 > >> pfn:0x34718 > >> flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) > >> page_type: f5(slab) > >> raw: 00fff00000000000 ffff88801ac4f780 dead000000000122 0000000000000000 > >> raw: 0000000000000000 00000000802a002a 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 > >> 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5823, > >> tgid 5823 (syz-executor352), ts 65548803787, free_ts 65433386693 > >> set_page_owner include/linux/page_owner.h:32 [inline] > >> post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1549 > >> prep_new_page mm/page_alloc.c:1557 [inline] > >> get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3475 > >> __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4752 > >> alloc_pages_mpol+0x30e/0x550 mm/mempolicy.c:2270 > >> alloc_slab_page mm/slub.c:2408 [inline] > >> allocate_slab+0x8f/0x3a0 mm/slub.c:2574 > >> new_slab mm/slub.c:2627 [inline] > >> ___slab_alloc+0xc27/0x14a0 mm/slub.c:3815 > >> __slab_alloc+0x58/0xa0 mm/slub.c:3905 > >> __slab_alloc_node mm/slub.c:3980 [inline] > >> slab_alloc_node mm/slub.c:4141 [inline] > >> kmem_cache_alloc_noprof+0x268/0x380 mm/slub.c:4160 > >> ptlock_alloc mm/memory.c:7026 [inline] > >> ptlock_init include/linux/mm.h:2971 [inline] > >> pmd_ptlock_init include/linux/mm.h:3078 [inline] > >> pagetable_pmd_ctor include/linux/mm.h:3116 [inline] > >> pmd_alloc_one_noprof include/asm-generic/pgalloc.h:141 [inline] > >> __pmd_alloc+0x10b/0x670 mm/memory.c:6436 > >> pmd_alloc include/linux/mm.h:2862 [inline] > >> copy_pmd_range+0x7352/0x77a0 mm/memory.c:1241 > >> copy_pud_range mm/memory.c:1298 [inline] > >> copy_p4d_range mm/memory.c:1322 [inline] > >> copy_page_range+0x99f/0xe90 mm/memory.c:1420 > >> dup_mmap kernel/fork.c:751 [inline] > >> dup_mm kernel/fork.c:1693 [inline] > >> copy_mm+0x12d2/0x2060 kernel/fork.c:1742 > >> copy_process+0x1845/0x3d80 kernel/fork.c:2393 > >> kernel_clone+0x226/0x8e0 kernel/fork.c:2805 > >> __do_sys_clone kernel/fork.c:2948 [inline] > >> __se_sys_clone kernel/fork.c:2932 [inline] > >> __x64_sys_clone+0x258/0x2a0 kernel/fork.c:2932 > >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] > >> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > >> page last free pid 6052 tgid 6051 stack trace: > >> reset_page_owner include/linux/page_owner.h:25 [inline] > >> free_pages_prepare mm/page_alloc.c:1127 [inline] > >> free_frozen_pages+0xe0d/0x10e0 mm/page_alloc.c:2658 > >> __folio_put+0x2b3/0x360 mm/swap.c:112 > >> __tlb_remove_table arch/x86/include/asm/tlb.h:34 [inline] > >> __tlb_remove_table_free mm/mmu_gather.c:227 [inline] > >> tlb_remove_table_rcu+0x76/0xf0 mm/mmu_gather.c:282 > >> rcu_do_batch kernel/rcu/tree.c:2567 [inline] > >> rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2823 > >> handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561 > >> __do_softirq kernel/softirq.c:595 [inline] > >> invoke_softirq kernel/softirq.c:435 [inline] > >> __irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662 > >> irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 > >> instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 > >> [inline] > >> sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 > >> asm_sysvec_apic_timer_interrupt+0x1a/0x20 > >> arch/x86/include/asm/idtentry.h:702 > >> > >> Memory state around the buggy address: > >> ffff888034718800: 00 00 00 00 fc fc fc fc 00 00 00 00 00 00 00 00 > >> ffff888034718880: fc fc fc fc 00 00 00 00 00 00 00 00 fc fc fc fc > >>> ffff888034718900: 00 00 00 00 00 00 00 00 fc fc fc fc fa fb fb fb > >> ^ > >> ffff888034718980: fb fb fb fb fc fc fc fc fa fb fb fb fb fb fb fb > >> ffff888034718a00: fc fc fc fc 00 00 00 00 00 00 00 00 fc fc fc fc > >> ================================================================== > >> > >> > >> --- > >> 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@xxxxxxxxxxxxxxxx. > >> > >> syzbot will keep track of this issue. See: > >> https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > >> For information about bisection process see: > >> https://goo.gl/tpsmEJ#bisection > >> > >> 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. > > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git > mm-unstable > > diff --git a/mm/memory.c b/mm/memory.c > index 83fd35c034d7a..28526a4205d1b 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -7023,7 +7023,7 @@ static struct kmem_cache *page_ptl_cachep; > void __init ptlock_cache_init(void) > { > page_ptl_cachep = kmem_cache_create("page->ptl", > sizeof(spinlock_t), 0, > - SLAB_PANIC, NULL); > + SLAB_PANIC|SLAB_TYPESAFE_BY_RCU, NULL); Note that `SLAB_TYPESAFE_BY_RCU` works by freeing the entire slab (the page containing the objects) with RCU, not individual objects. So I don't think this would work. A PTL object can be re-allocated to someone else, and that new user can re-initialize it. So trying to concurrently lock it under RCU read lock would also be use-after-free. > } > > bool ptlock_alloc(struct ptdesc *ptdesc) > > >> > >> 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 >
