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Message-ID: <c3379af4-cfc3-41e8-89fb-1ad5292d952a@bytedance.com>
Date: Mon, 9 Dec 2024 15:00:04 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: syzbot <syzbot+1c58afed1cfd2f57efee@...kaller.appspotmail.com>
Cc: David Hildenbrand <david@...hat.com>, Jann Horn <jannh@...gle.com>,
Hugh Dickins <hughd@...gle.com>, Muchun Song <muchun.song@...ux.dev>,
akpm@...ux-foundation.org, bp@...en8.de, dave.hansen@...ux.intel.com,
hpa@...or.com, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
mingo@...hat.com, syzkaller-bugs@...glegroups.com, tglx@...utronix.de,
x86@...nel.org
Subject: Re: [syzbot] [mm?] KASAN: slab-use-after-free Read in move_pages_pte
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@...edance.com>
>> 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@...kaller.appspotmail.com
>> 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@...glegroups.com.
>>
>> 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);
}
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
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