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Subject: Re: [PATCH 1/1] NFSv4.2: fix LISTXATTR buffer receive size
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <CAN-5tyEyQbmc-oefF+-PdtdcS7GJ9zmJk71Dk8EED0upcorqaA@mail.gmail.com>
Date:   Thu, 19 Nov 2020 09:37:13 -0500
Cc:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Frank van der Linden <fllinden@amazon.com>
Content-Transfer-Encoding: quoted-printable
Message-Id: <07AF9A5C-BC42-4F66-A153-19A410D312E1@oracle.com>
References: <20201113190851.7817-1-olga.kornievskaia@gmail.com>
 <99874775-A18C-4832-A2F0-F2152BE5CE32@oracle.com>
 <CAN-5tyEyQbmc-oefF+-PdtdcS7GJ9zmJk71Dk8EED0upcorqaA@mail.gmail.com>
To:     Olga Kornievskaia <olga.kornievskaia@gmail.com>
Precedence: bulk

Hi Olga-

> On Nov 18, 2020, at 4:44 PM, Olga Kornievskaia =
<olga.kornievskaia@gmail.com> wrote:
>=20
> Hi Chuck,
>=20
> The first problem I found was from 5.10-rc3 testing was from the fact
> that tail's iov_len was set to -4 and reply_chunk was trying to call
> rpcrdma_convert_kvec() for a tail that didn't exist.
>=20
> Do you see issues with this fix?
>=20
> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
> index 71e03b930b70..2e6a228abb95 100644
> --- a/net/sunrpc/xdr.c
> +++ b/net/sunrpc/xdr.c
> @@ -193,7 +193,7 @@ xdr_inline_pages(struct xdr_buf *xdr, unsigned int =
offset,
>=20
>        tail->iov_base =3D buf + offset;
>        tail->iov_len =3D buflen - offset;
> -       if ((xdr->page_len & 3) =3D=3D 0)
> +       if ((xdr->page_len & 3) =3D=3D 0 && tail->iov_len)
>                tail->iov_len -=3D sizeof(__be32);
>=20
>        xdr->buflen +=3D len;

It's not clear to me whether only the listxattrs encoder is
not providing a receive tail kvec, or whether all the encoders
fail to provide a tail in this case.


> This one fixes KASAN's reported problem of added at the end of this =
message.
>=20
> The next problem that I can't figure out yet is another KASAN's report
> during the completion of the request.
>=20
> [   99.610666] BUG: KASAN: wild-memory-access in
> rpcrdma_complete_rqst+0x41b/0x680 [rpcrdma]
> [   99.617947] Write of size 4 at addr 0005088000000000 by task =
kworker/1:1H/490
>=20
>=20
> This is the KASAN for the negative tail problem:
> [  665.767611] =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> [  665.772202] BUG: KASAN: slab-out-of-bounds in
> rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.777860] Write of size 8 at addr ffff88803ded9b70 by task =
fsstress/3123
> [  665.783754]
> [  665.784981] CPU: 0 PID: 3123 Comm: fsstress Not tainted 5.10.0-rc3+ =
#38
> [  665.790534] Hardware name: VMware, Inc. VMware Virtual
> Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
> [  665.798538] Call Trace:
> [  665.800398]  dump_stack+0x7c/0xa2
> [  665.802647]  ? rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.808145]  print_address_description.constprop.7+0x1e/0x230
> [  665.812543]  ? record_print_text.cold.38+0x11/0x11
> [  665.816093]  ? _raw_write_lock_irqsave+0xe0/0xe0
> [  665.819257]  ? rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.823368]  ? rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.827837]  kasan_report.cold.9+0x37/0x7c
> [  665.830076]  ? rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.834066]  rpcrdma_convert_kvec.isra.29+0x4a/0xc4 [rpcrdma]
> [  665.837342]  rpcrdma_convert_iovs.isra.30.cold.41+0x9b/0xa0 =
[rpcrdma]
> [  665.841766]  ? decode_read_list+0x40/0x40 [rpcrdma]
> [  665.845063]  ? _raw_spin_lock_irqsave+0x80/0xe0
> [  665.848444]  ? xdr_reserve_space+0x12e/0x360 [sunrpc]
> [  665.852186]  ? xdr_init_encode+0x104/0x130 [sunrpc]
> [  665.855305]  rpcrdma_marshal_req.cold.43+0x39/0x1fa [rpcrdma]
> [  665.859771]  ? _raw_spin_lock+0x7a/0xd0
> [  665.862516]  ? rpcrdma_prepare_send_sges+0x7e0/0x7e0 [rpcrdma]
> [  665.866533]  ? call_bind+0x60/0xf0 [sunrpc]
> [  665.869382]  xprt_rdma_send_request+0x79/0x190 [rpcrdma]
> [  665.872965]  xprt_transmit+0x2ae/0x6c0 [sunrpc]
> [  665.875955]  ? call_bind+0xf0/0xf0 [sunrpc]
> [  665.878372]  call_transmit+0xdd/0x110 [sunrpc]
> [  665.881539]  ? call_bind+0xf0/0xf0 [sunrpc]
> [  665.884629]  __rpc_execute+0x11c/0x6e0 [sunrpc]
> [  665.888300]  ? trace_event_raw_event_xprt_cong_event+0x270/0x270 =
[sunrpc]
> [  665.893935]  ? rpc_make_runnable+0x54/0xe0 [sunrpc]
> [  665.898021]  rpc_run_task+0x29c/0x2c0 [sunrpc]
> [  665.901142]  nfs4_call_sync_custom+0xc/0x40 [nfsv4]
> [  665.904903]  nfs4_do_call_sync+0x114/0x160 [nfsv4]
> [  665.908633]  ? nfs4_call_sync_custom+0x40/0x40 [nfsv4]
> [  665.913094]  ? __alloc_pages_nodemask+0x200/0x410
> [  665.916831]  ? kasan_unpoison_shadow+0x30/0x40
> [  665.920393]  ? __kasan_kmalloc.constprop.8+0xc1/0xd0
> [  665.924403]  _nfs42_proc_listxattrs+0x1f6/0x2f0 [nfsv4]
> [  665.928552]  ? kasan_set_free_info+0x1b/0x30
> [  665.932283]  ? nfs42_offload_cancel_done+0x50/0x50 [nfsv4]
> [  665.936240]  ? _raw_spin_lock+0x7a/0xd0
> [  665.938677]  nfs42_proc_listxattrs+0xf4/0x150 [nfsv4]
> [  665.942532]  ? nfs42_proc_setxattr+0x150/0x150 [nfsv4]
> [  665.946410]  ? nfs4_xattr_cache_list+0x21/0x120 [nfsv4]
> [  665.950095]  nfs4_listxattr+0x34d/0x3d0 [nfsv4]
> [  665.952951]  ? _nfs4_proc_access+0x260/0x260 [nfsv4]
> [  665.956383]  ? __ia32_sys_rename+0x40/0x40
> [  665.959559]  ? __ia32_sys_lstat+0x30/0x30
> [  665.962519]  ? __check_object_size+0x178/0x220
> [  665.965830]  ? strncpy_from_user+0xe9/0x230
> [  665.968401]  ? security_inode_listxattr+0x20/0x60
> [  665.971653]  listxattr+0xd1/0xf0
> [  665.974065]  path_listxattr+0xa1/0x100
> [  665.977023]  ? listxattr+0xf0/0xf0
> [  665.979305]  do_syscall_64+0x33/0x40
> [  665.981561]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [  665.985559] RIP: 0033:0x7fe3f5a1fc8b
> [  665.988136] Code: f0 ff ff 73 01 c3 48 8b 0d fa 21 2c 00 f7 d8 64
> 89 01 48 83 c8 ff c3 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 c2 00 00
> 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d cd 21 2c 00 f7 d8 64 89
> 01 48
> [  666.002248] RSP: 002b:00007ffc826128e8 EFLAGS: 00000206 ORIG_RAX:
> 00000000000000c2
> [  666.007760] RAX: ffffffffffffffda RBX: 0000000000000021 RCX: =
00007fe3f5a1fc8b
> [  666.012999] RDX: 0000000000000000 RSI: 0000000000000000 RDI: =
00000000016eaf70
> [  666.018963] RBP: 00000000000001f4 R08: 0000000000000000 R09: =
00007ffc82612537
> [  666.025553] R10: 0000000000000004 R11: 0000000000000206 R12: =
0000000000000021
> [  666.030600] R13: 0000000000403e60 R14: 0000000000000000 R15: =
0000000000000000
> [  666.035780]
> [  666.036906] Allocated by task 2837:
> [  666.039447]  kasan_save_stack+0x19/0x40
> [  666.042815]  __kasan_kmalloc.constprop.8+0xc1/0xd0
> [  666.046626]  rpcrdma_req_create+0x58/0x1f0 [rpcrdma]
> [  666.050283]  rpcrdma_buffer_create+0x217/0x270 [rpcrdma]
> [  666.053727]  xprt_setup_rdma+0x1a3/0x2c0 [rpcrdma]
> [  666.057287]  xprt_create_transport+0xc7/0x300 [sunrpc]
> [  666.061656]  rpc_create+0x185/0x360 [sunrpc]
> [  666.064803]  nfs_create_rpc_client+0x2d9/0x350 [nfs]
> [  666.068233]  nfs4_init_client+0x111/0x3d0 [nfsv4]
> [  666.071563]  nfs4_set_client+0x18c/0x2b0 [nfsv4]
> [  666.075287]  nfs4_create_server+0x303/0x590 [nfsv4]
> [  666.079563]  nfs4_try_get_tree+0x60/0xe0 [nfsv4]
> [  666.082835]  vfs_get_tree+0x45/0x120
> [  666.085165]  path_mount+0x8da/0xcc0
> [  666.087352]  do_mount+0xcb/0xf0
> [  666.089377]  __x64_sys_mount+0xf4/0x110
> [  666.091894]  do_syscall_64+0x33/0x40
> [  666.094215]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [  666.097181]
> [  666.098548] The buggy address belongs to the object at =
ffff88803ded8000
> [  666.098548]  which belongs to the cache kmalloc-8k of size 8192
> [  666.108266] The buggy address is located 7024 bytes inside of
> [  666.108266]  8192-byte region [ffff88803ded8000, ffff88803deda000)
> [  666.115709] The buggy address belongs to the page:
> [  666.118516] page:00000000e08a579f refcount:1 mapcount:0
> mapping:0000000000000000 index:0x0 pfn:0x3ded8
> [  666.124078] head:00000000e08a579f order:3 compound_mapcount:0
> compound_pincount:0
> [  666.130104] flags: 0xfffffc0010200(slab|head)
> [  666.133692] raw: 000fffffc0010200 dead000000000100 dead000000000122
> ffff88800104ee40
> [  666.139286] raw: 0000000000000000 0000000000020002 00000001ffffffff
> 0000000000000000
> [  666.145052] page dumped because: kasan: bad access detected
> [  666.149341]
> [  666.150408] Memory state around the buggy address:

--
Chuck Lever