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Date: Fri, 27 Mar 2020 10:04:40 +0000
From: 陈安庆 <chenanqing@...o.com>
To: Ilya Dryomov <idryomov@...il.com>
CC: LKML <linux-kernel@...r.kernel.org>,
netdev <netdev@...r.kernel.org>,
Ceph Development <ceph-devel@...r.kernel.org>,
"kuba@...nel.org" <kuba@...nel.org>, Sage Weil <sage@...hat.com>,
Jeff Layton <jlayton@...nel.org>
Subject: Re: [PATCH] scsi: libiscsi: we should take compound page into account
also
On Fri, Mar 27, 2020 at 9:36 AM <chenanqing@...o.com> wrote:
>
> From: Chen Anqing <chenanqing@...o.com>
> To: Ilya Dryomov <idryomov@...il.com>
> Cc: Jeff Layton <jlayton@...nel.org>,
> Sage Weil <sage@...hat.com>,
> Jakub Kicinski <kuba@...nel.org>,
> ceph-devel@...r.kernel.org,
> netdev@...r.kernel.org,
> linux-kernel@...r.kernel.org,
> chenanqing@...o.com
> Subject: [PATCH] libceph: we should take compound page into account
> also
> Date: Fri, 27 Mar 2020 04:36:30 -0400
> Message-Id: <20200327083630.36296-1-chenanqing@...o.com>
> X-Mailer: git-send-email 2.18.2
>
> the patch is occur at a real crash,which slab is come from a compound
> page,so we need take the compound page into account also.
> fixed commit 7e241f647dc7 ("libceph: fall back to sendmsg for slab pages")'
>
> Signed-off-by: Chen Anqing <chenanqing@...o.com>
> ---
> net/ceph/messenger.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index
> f8ca5edc5f2c..e08c1c334cd9 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -582,7 +582,7 @@ static int ceph_tcp_sendpage(struct socket *sock, struct page *page,
> * coalescing neighboring slab objects into a single frag which
> * triggers one of hardened usercopy checks.
> */
> - if (page_count(page) >= 1 && !PageSlab(page))
> + if (page_count(page) >= 1 && !PageSlab(compound_head(page)))
> sendpage = sock->ops->sendpage;
> else
> sendpage = sock_no_sendpage;
>Hi Chen,
>AFAICT compound pages should already be taken into account, because PageSlab is defined as:
>
> __PAGEFLAG(Slab, slab, PF_NO_TAIL)
>
> #define __PAGEFLAG(uname, lname, policy) \
> TESTPAGEFLAG(uname, lname, policy) \
> __SETPAGEFLAG(uname, lname, policy) \
> __CLEARPAGEFLAG(uname, lname, policy)
>
> #define TESTPAGEFLAG(uname, lname, policy) \
> static __always_inline int Page##uname(struct page *page) \
> { return test_bit(PG_##lname, &policy(page, 0)->flags); }
>
> and PF_NO_TAIL policy is defined as:
> #define PF_NO_TAIL(page, enforce) ({ \
> VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
> PF_POISONED_CHECK(compound_head(page)); })
> So compound_head() is called behind the scenes.
>Could you please explain what crash did you observe in more detail?
>Perhaps you backported this patch to an older kernel?
>Thanks,
> Ilya
Hi llya,
thank you for you reply so quickly.
I have apply the patch in my server ,it's work fine ,so I thought it should be pushed to the community, but I Know nothing about the
PageSlab has been changed ,because I use the 3.10.0- all the time ,sorry for that. i also send patch to scsi group also.
my crash is writed below:
[85774.558604] usercopy: kernel memory exposure attempt detected from ffff9cba0bf75400 (kmalloc-512) (1024 bytes)
[85774.559261] ------------[ cut here ]------------
[85774.559839] kernel BUG at mm/usercopy.c:72!
[85774.560367] invalid opcode: 0000 [#1] SMP
[85774.560879] Modules linked in: cmac arc4 md4 nls_utf8 cifs ccm dns_resolver xfs iscsi_tcp libiscsi_tcp libiscsi iptable_raw iptable_mangle sch_sfq sch_htb scsi_transport_iscsi veth ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_comment xt_mark iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter xt_conntrack nf_nat nf_conntrack br_netfilter bridge stp llc dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c loop bonding fuse sunrpc dm_mirror dm_region_hash dm_log dm_mod dell_smbios dell_wmi_descriptor iTCO_wdt iTCO_vendor_support dcdbas skx_edac intel_powerclamp coretemp intel_rapl iosf_mbi kvm_intel kvm irqbypass crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd ipmi_ssif sg pcspkr mei_me lpc_ich i2c_i801 mei wmi ipmi_si
[85774.564343] ipmi_devintf ipmi_msghandler acpi_pad acpi_power_meter ip_tables ext4 mbcache jbd2 sd_mod crc_t10dif crct10dif_generic crct10dif_pclmul crct10dif_common crc32c_intel mgag200 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm megaraid_sas drm ixgbe ahci igb drm_panel_orientation_quirks libahci mdio libata ptp pps_core dca i2c_algo_bit nfit libnvdimm
[85774.566809] CPU: 9 PID: 28054 Comm: tgtd Kdump: loaded Not tainted 3.10.0-957.27.2.el7.x86_64 #1
[85774.567446] Hardware name: Dell Inc. PowerEdge R740/0YNX56, BIOS 2.4.8 11/26/2019
[85774.568094] task: ffff9cb12e1e0000 ti: ffff9cb124224000 task.ti: ffff9cb124224000
[85774.568754] RIP: 0010:[<ffffffff9803f557>] [<ffffffff9803f557>] __check_object_size+0x87/0x250
[85774.569419] RSP: 0018:ffff9cb124227b98 EFLAGS: 00010246
[85774.570072] RAX: 0000000000000062 RBX: ffff9cba0bf75400 RCX: 0000000000000000
[85774.570723] RDX: 0000000000000000 RSI: ffff9cc13bf13898 RDI: ffff9cc13bf13898
[85774.571372] RBP: ffff9cb124227bb8 R08: 0000000000000000 R09: ffff9cb1313e6f00
[85774.572017] R10: 000000000003bc95 R11: 0000000000000001 R12: 0000000000000400
[85774.572669] R13: 0000000000000001 R14: ffff9cba0bf75800 R15: 0000000000000400
[85774.573325] FS: 00007f41a122a740(0000) GS:ffff9cc13bf00000(0000) knlGS:0000000000000000
[85774.573994] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[85774.574655] CR2: 0000000003236fe0 CR3: 0000001023138000 CR4: 00000000007607e0
[85774.575314] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[85774.575964] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[85774.576609] PKRU: 55555554
[85774.577242] Call Trace:
[85774.577880] [<ffffffff9818dd9d>] memcpy_toiovec+0x4d/0xb0
[85774.578531] [<ffffffff9842c858>] skb_copy_datagram_iovec+0x128/0x280
[85774.579190] [<ffffffff9849372a>] tcp_recvmsg+0x22a/0xb30
[85774.579838] [<ffffffff984c2340>] inet_recvmsg+0x80/0xb0
[85774.580474] [<ffffffff9841a6ec>] sock_aio_read.part.9+0x14c/0x170
[85774.581097] [<ffffffff9841a731>] sock_aio_read+0x21/0x30
[85774.581714] [<ffffffff98041b33>] do_sync_read+0x93/0xe0
[85774.582328] [<ffffffff98042615>] vfs_read+0x145/0x170
[85774.582934] [<ffffffff9804342f>] SyS_read+0x7f/0xf0
[85774.583543] [<ffffffff98576ddb>] system_call_fastpath+0x22/0x27
[85774.584158] Code: 45 d1 48 c7 c6 05 c3 87 98 48 c7 c1 f6 57 88 98 48 0f 45 f1 49 89 c0 4d 89 e1 48 89 d9 48 c7 c7 00 27 88 98 31 c0 e8 30 e4 51 00 <0f> 0b 0f 1f 80 00 00 00 00 48 c7 c0 00 00 e0 97 4c 39 f0 73 0d
[85774.585495] RIP [<ffffffff9803f557>] __check_object_size+0x87/0x250
[85774.586135] RSP <ffff9cb124227b98>
crash> dis -l skb_copy_datagram_iovec
/usr/src/debug/kernel-3.10.0-957.27.2.el7/linux-3.10.0-957.27.2.el7.x86_64/net/core/datagram.c: 395
0xffffffff9842c730 <skb_copy_datagram_iovec>: nopl 0x0(%rax,%rax,1) [FTRACE NOP]
0xffffffff9842c735 <skb_copy_datagram_iovec+5>: push %rbp
0xffffffff9842c736 <skb_copy_datagram_iovec+6>: mov %rsp,%rbp
0xffffffff9842c739 <skb_copy_datagram_iovec+9>: push %r15
0xffffffff9842c73b <skb_copy_datagram_iovec+11>: push %r14
0xffffffff9842c73d <skb_copy_datagram_iovec+13>: mov %rdi,%r14
0xffffffff9842c740 <skb_copy_datagram_iovec+16>: push %r13
0xffffffff9842c742 <skb_copy_datagram_iovec+18>: push %r12
0xffffffff9842c744 <skb_copy_datagram_iovec+20>: mov %esi,%r12d
0xffffffff9842c747 <skb_copy_datagram_iovec+23>: push %rbx----------------：skb is store in rbx and I get it from stack
0xffffffff9842c748 <skb_copy_datagram_iovec+24>: mov %ecx,%ebx
0xffffffff9842c74a <skb_copy_datagram_iovec+26>: sub $0x28,%rsp
crash> sk_buff.len ffff9cb0e3b388f8
len = 1024
crash> sk_buff.data_len ffff9cb0e3b388f8
data_len = 1024
crash> sk_buff.head ffff9cb0e3b388f8
head = 0xffff9cbf9c679400 ""
crash> sk_buff.end ffff9cb0e3b388f8 -x
end = 0x2c0
crash> px 0xffff9cbf9c679400 + 0x2c0
$5 = 0xffff9cbf9c6796c0
crash> skb_shared_info 0xffff9cbf9c6796c0
struct skb_shared_info {
nr_frags = 1 '\001',
tx_flags = 32 ' ',
gso_size = 0,
gso_segs = 1,
gso_type = 0,
frag_list = 0x0,
hwtstamps = {
crash> skb_shared_info.frags 0xffff9cbf9c6796c0
frags = {{
page = {
p = 0xfffff597a42fdd40-----it the page which store the data
},
page_offset = 1024,
size = 1024
}, {
crash> kmem ffff9cba0bf75400------------the address which is reported in the bugon line，
CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
ffff9ca27fc07600 kmalloc-512 512 242454 464512 7258 32k
SLAB MEMORY NODE TOTAL ALLOCATED FREE
fffff597a42fdc00 ffff9cba0bf70000 1 64 59 5
FREE / [ALLOCATED]
[ffff9cba0bf75400]
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffff597a42fdd40 190bf75000 0 0 0 6fffff00008000 tail
and I found the page is not the head page ,it is a tail page of compound page.
so I search the linux code ,I get the patch:
commit 7e241f647dc7 ("libceph: fall back to sendmsg for slab pages")'
commit 08b11eaccfcf ("scsi: libiscsi: fall back to sendmsg for slab pages").
sorry again for troubling you.
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