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Subject: Re: linux-next: not-present page at swap_vma_readahead()
From:   Qian Cai <cai@lca.pw>
In-Reply-To: <62A0ACFC-E023-4269-8121-F96B879A8C51@lca.pw>
Date:   Tue, 14 Apr 2020 17:22:54 -0400
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Minchan Kim <minchan@kernel.org>,
        Huang Ying <ying.huang@intel.com>,
        Hugh Dickins <hughd@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
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Message-Id: <81F06AA9-F25B-4342-9CF7-2763AC394A18@lca.pw>
References: <62A0ACFC-E023-4269-8121-F96B879A8C51@lca.pw>
To:     Linux-MM <linux-mm@kvack.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Apr 14, 2020, at 10:32 AM, Qian Cai <cai@lca.pw> wrote:
>=20
> Fuzzers are unhappy. Thoughts?

This is rather to reproduce. All the traces so far are from =
copy_from_user() to trigger a page fault,
and then it dereferences a bad pte in swap_vma_readahead(),

	for (i =3D 0, pte =3D ra_info.ptes; i < ra_info.nr_pte;
	     i++, pte++) {
		pentry =3D *pte;   <=E2=80=94 crashed here.
		if (pte_none(pentry))

[12561.167450][ T8470] Unable to handle kernel paging request at virtual =
address ffff000eec8dffe8
[12561.176391][ T8470] Mem abort info:
[12561.179916][ T8470]   ESR =3D 0x96000007
[12561.183702][ T8470]   EC =3D 0x25: DABT (current EL), IL =3D 32 bits
[12561.189897][ T8470]   SET =3D 0, FnV =3D 0
[12561.193681][ T8470]   EA =3D 0, S1PTW =3D 0
[12561.197622][ T8470] Data abort info:
[12561.201232][ T8470]   ISV =3D 0, ISS =3D 0x00000007
[12561.205905][ T8470]   CM =3D 0, WnR =3D 0
[12561.209605][ T8470] swapper pgtable: 64k pages, 48-bit VAs, =
pgdp=3D00000000813d0000
[12561.217231][ T8470] [ffff000eec8dffe8] pgd=3D00000097fcfd0003, =
pud=3D00000097fcfd0003, pmd=3D00000097fcc10003, pte=3D0068000f6c8d0712
[12561.229049][ T8470] Internal error: Oops: 96000007 [#1] SMP
[12561.234628][ T8470] Modules linked in: nfnetlink thunderx2_pmu =
processor ip_tables xfs libcrc32c sd_mod ahci libahci mlx5_core libata =
dm_mirror dm_region_hash dm_log dm_mod efivarfs
[12561.250854][ T8470] CPU: 147 PID: 8470 Comm: trinity-c147 Tainted: G  =
           L    5.7.0-rc1-next-20200414 #5
[12561.261031][ T8470] Hardware name: HPE Apollo 70             =
/C01_APACHE_MB         , BIOS L50_5.13_1.11 06/18/2019
[12561.271472][ T8470] pstate: 60400009 (nZCv daif +PAN -UAO)
[12561.276978][ T8470] pc : swap_vma_readahead+0x360/0x568
[12561.282207][ T8470] lr : swap_vma_readahead+0x360/0x568
[12561.287442][ T8470] sp : e4ff000eec8af7f0
[12561.291461][ T8470] x29: e4ff000eec8af8b0 x28: 0dff000eec868ce0=20
[12561.297476][ T8470] x27: 0000000000000000 x26: 0400000000000001=20
[12561.303490][ T8470] x25: e4ff000eec8afa48 x24: ffff000eec8dffe8=20
[12561.309503][ T8470] x23: e4ff000eec8af80c x22: 0dff000eec868c30=20
[12561.315517][ T8470] x21: e4ff000eec8afa30 x20: 0000000000000000=20
[12561.321529][ T8470] x19: 0000000000100cca x18: 0000000000000000=20
[12561.327541][ T8470] x17: 0000000000000000 x16: 0000000000000000=20
[12561.333553][ T8470] x15: 0000000000000000 x14: 0000000000000000=20
[12561.339567][ T8470] x13: 0000000000000000 x12: 0000000000000000=20
[12561.345580][ T8470] x11: 00000000000000e4 x10: ffff8000eec8af82=20
[12561.351593][ T8470] x9 : ffff8000eec8af81 x8 : 0000000000000001=20
[12561.357605][ T8470] x7 : 0000000000000000 x6 : 0000000000000000=20
[12561.363617][ T8470] x5 : e4ff000eec8af848 x4 : e4ff000eec8af850=20
[12561.369630][ T8470] x3 : ffff90001042ec64 x2 : 0000000000000000=20
[12561.375648][ T8470] x1 : 0000000000000008 x0 : 0000000000000001=20
[12561.381679][ T8470] Call trace:
[12561.384849][ T8470]  swap_vma_readahead+0x360/0x568
[12561.389747][ T8470]  swapin_readahead+0x9c/0xc0
[12561.394308][ T8470]  do_swap_page+0x314/0xccc
[12561.398684][ T8470]  handle_pte_fault+0x7a0/0x14d0
[12561.403494][ T8470]  handle_mm_fault+0x4ac/0x5d0
[12561.408143][ T8470]  do_page_fault+0x45c/0x708
[12561.412626][ T8470]  do_translation_fault+0x60/0x98
[12561.417535][ T8470]  do_mem_abort+0x58/0xf4
[12561.421754][ T8470]  el1_sync_handler+0x9c/0x100
[12561.426403][ T8470]  el1_sync+0xb4/0x180
[12561.430360][ T8470]  __arch_copy_from_user+0x24/0x240
[12561.435446][ T8470]  __arm64_sys_recvmmsg+0xa0/0x1a8
[12561.440433][ T8470]  do_el0_svc+0x128/0x1dc
[12561.444641][ T8470]  el0_sync_handler+0x150/0x250
[12561.449365][ T8470]  el0_sync+0x164/0x180
[12561.453408][ T8470] Code: 6b08029f 54000842 aa1803e0 940101ef =
(f9400308)=20
[12561.460883][ T8470] ---[ end trace d7b340909510bdcf ]---
[12561.466220][ T8470] Kernel panic - not syncing: Fatal exception
[12561.472743][ T8470] SMP: stopping secondary CPUs
[12561.477581][ T8470] Kernel Offset: disabled
[12561.481770][ T8470] CPU features: 0x006002,61000c38
[12561.486648][ T8470] Memory Limit: none
[12561.490729][ T8470] ---[ end Kernel panic - not syncing: Fatal =
exception ]---

>=20
> [34944.838318][T48906] BUG: unable to handle page fault for address: =
ffff888cb196bfe8
> [34944.845970][T48906] #PF: supervisor read access in kernel mode
> [34944.847199][T50168] futex_wake_op: trinity-c58 tries to shift op by =
-1; fix this program
> [34944.851855][T48906] #PF: error_code(0x0000) - not-present page
> [34944.851866][T48906] PGD f63401067 P4D f63401067 PUD 1079630067 PMD =
10794a3067 PTE 800ffff34e694060
> [34944.874964][T48906] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
> [34944.881289][T48906] CPU: 72 PID: 48906 Comm: trinity-c85 Tainted: G =
            L    5.7.0-rc1-next-20200414+ #8
> [34944.891559][T48906] Hardware name: HPE ProLiant DL385 =
Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
> [34944.900860][T48906] RIP: 0010:swapin_readahead+0x40a/0x85f
> swap_vma_readahead at mm/swap_state.c:741
> (inlined by) swapin_readahead at mm/swap_state.c:785
> [34944.906394][T48906] Code: 6c 24 70 44 8b 64 24 0c 4c 89 6c 24 18 eb =
13 41 83 c4 01 49 83 c6 08 44 3b 64 24 20 0f 84 38 03 00 00 4c 89 f7 e8 =
66 74 04 00 <4d> 8b 3e 49 f7 c7 9f ff ff ff 74 d9 48 c7 c7 a0 83 23 91 =
e8 4e 74
> [34944.925989][T48906] RSP: 0018:ffffc9002622f620 EFLAGS: 00010246
> [34944.931960][T48906] RAX: 0000000000000000 RBX: ffffc9002622f8d8 =
RCX: ffffffff902370aa
> [34944.939849][T48906] RDX: dffffc0000000000 RSI: 0000000000000001 =
RDI: ffff888cb196bfe8
> [34944.947737][T48906] RBP: ffffc9002622f758 R08: 0000000000000000 =
R09: ffffed112d8078e7
> [34944.955625][T48906] R10: ffff88896c03c737 R11: ffffed112d8078e6 =
R12: 0000000000000000
> [34944.963580][T48906] R13: ffffc9002622f690 R14: ffff888cb196bfe8 =
R15: ffff888cb196c000
> [34944.971479][T48906] FS:  00007f17c465a740(0000) =
GS:ffff889032c00000(0000) knlGS:0000000000000000
> [34944.980329][T48906] CS:  0010 DS: 0000 ES: 0000 CR0: =
0000000080050033
> [34944.986820][T48906] CR2: ffff888cb196bfe8 CR3: 0000000c17964000 =
CR4: 00000000003406e0
> [34944.994709][T48906] Call Trace:
> [34944.997895][T48906]  ? exit_swap_address_space+0x160/0x160
> [34945.003429][T48906]  ? lookup_swap_cache+0x144/0x410
> [34945.008516][T48906]  ? swapcache_prepare+0x20/0x20
> [34945.013352][T48906]  do_swap_page+0x4ef/0xe70
> do_swap_page at mm/memory.c:3141
> [34945.017751][T48906]  ? unmap_mapping_range+0x30/0x30
> [34945.022763][T48906]  __handle_mm_fault+0xb80/0xbe0
> [34945.027601][T48906]  ? copy_page_range+0x420/0x420
> [34945.032438][T48906]  handle_mm_fault+0xdc/0x2e0
> [34945.037013][T48906]  do_page_fault+0x2cb/0x9d7
> [34945.041607][T48906]  page_fault+0x34/0x40
> [34945.045655][T48906] RIP: 0010:strncpy_from_user+0xc9/0x2a0
> [34945.051184][T48906] Code: 14 00 00 4c 01 e8 0f 92 c1 0f 82 45 01 00 =
00 48 39 c2 0f 82 3c 01 00 00 0f 01 cb 0f ae e8 49 83 fd 07 0f 86 b7 01 =
00 00 31 f6 <49> 8b 14 24 85 f6 0f 85 9b 01 00 00 49 8d 45 f8 4c 89 6d =
c0 49 89
> [34945.070775][T48906] RSP: 0018:ffffc9002622fb28 EFLAGS: 00050246
> [34945.076742][T48906] RAX: 0000000000000fe0 RBX: ffff888c17830040 =
RCX: 0000000000000000
> [34945.084626][T48906] RDX: 00007ffffffff000 RSI: 0000000000000000 =
RDI: ffff888c178314d0
> [34945.092516][T48906] RBP: ffffc9002622fb70 R08: 0000000000000fe0 =
R09: fffff940065ea9e1
> [34945.100402][T48906] R10: ffffea0032f54f07 R11: fffff940065ea9e0 =
R12: 0000000000000000
> [34945.108288][T48906] R13: 0000000000000fe0 R14: ffff888cbd53c060 =
R15: 0000000000000fe0
> [34945.116184][T48906]  ? strncpy_from_user+0x96/0x2a0
> [34945.121106][T48906]  getname_flags+0x6a/0x220
> [34945.125502][T48906]  do_renameat2+0x17c/0x7e0
> [34945.129895][T48906]  ? user_path_create+0x40/0x40
> [34945.134642][T48906]  ? register_lock_class+0xb40/0xb40
> [34945.139824][T48906]  ? match_held_lock+0x20/0x250
> [34945.144569][T48906]  ? find_held_lock+0xca/0xf0
> [34945.149140][T48906]  ? __kasan_check_read+0x11/0x20
> [34945.154062][T48906]  ? perf_syscall_enter+0xf9/0x370
> [34945.159065][T48906]  ? lock_downgrade+0x3e0/0x3e0
> [34945.163804][T48906]  ? check_flags.part.28+0x86/0x220
> [34945.168896][T48906]  ? rcu_read_lock_sched_held+0xac/0xe0
> [34945.174339][T48906]  ? do_syscall_64+0x79/0xaf0
> [34945.178907][T48906]  ? rcu_read_lock_bh_held+0xc0/0xc0
> [34945.184091][T48906]  __x64_sys_rename+0x3b/0x50
> [34945.188659][T48906]  do_syscall_64+0xcc/0xaf0
> [34945.193050][T48906]  ? perf_call_bpf_enter+0x1a0/0x1a0
> [34945.198230][T48906]  ? syscall_return_slowpath+0x580/0x580
> [34945.203760][T48906]  ? entry_SYSCALL_64_after_hwframe+0x3e/0xb3
> [34945.209725][T48906]  ? trace_hardirqs_off_caller+0x3a/0x150
> [34945.215340][T48906]  ? trace_hardirqs_off_thunk+0x1a/0x1c
> [34945.220780][T48906]  entry_SYSCALL_64_after_hwframe+0x49/0xb3
> [34945.226568][T48906] RIP: 0033:0x7f17c3f5c839
> [34945.230872][T48906] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f =
1f 40 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 8b 0d 1f f6 2c 00 f7 d8 64 =
89 01 48
> [34945.250461][T48906] RSP: 002b:00007fff822be2d8 EFLAGS: 00000246 =
ORIG_RAX: 0000000000000052
> [34945.258802][T48906] RAX: ffffffffffffffda RBX: 0000000000000052 =
RCX: 00007f17c3f5c839
> [34945.266685][T48906] RDX: 00000000000000e8 RSI: 0000000000000000 =
RDI: 0000000000000000