LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	"Ilya Lipnitskiy" <ilya.lipnitskiy@gmail.com>,
	"Hugh Dickins" <hughd@google.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"周琰杰  " <zhouyanjie@wanyeetech.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: [PATCH 4.14 28/52] mm: fix race by making init_zero_pfn() early_initcall
Date: Mon,  5 Apr 2021 10:53:54 +0200
Message-ID: <20210405085022.906274269@linuxfoundation.org> (raw)
In-Reply-To: <20210405085021.996963957@linuxfoundation.org>

From: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>

commit e720e7d0e983bf05de80b231bccc39f1487f0f16 upstream.

There are code paths that rely on zero_pfn to be fully initialized
before core_initcall.  For example, wq_sysfs_init() is a core_initcall
function that eventually results in a call to kernel_execve, which
causes a page fault with a subsequent mmput.  If zero_pfn is not
initialized by then it may not get cleaned up properly and result in an
error:

  BUG: Bad rss-counter state mm:(ptrval) type:MM_ANONPAGES val:1

Here is an analysis of the race as seen on a MIPS device. On this
particular MT7621 device (Ubiquiti ER-X), zero_pfn is PFN 0 until
initialized, at which point it becomes PFN 5120:

  1. wq_sysfs_init calls into kobject_uevent_env at core_initcall:
       kobject_uevent_env+0x7e4/0x7ec
       kset_register+0x68/0x88
       bus_register+0xdc/0x34c
       subsys_virtual_register+0x34/0x78
       wq_sysfs_init+0x1c/0x4c
       do_one_initcall+0x50/0x1a8
       kernel_init_freeable+0x230/0x2c8
       kernel_init+0x10/0x100
       ret_from_kernel_thread+0x14/0x1c

  2. kobject_uevent_env() calls call_usermodehelper_exec() which executes
     kernel_execve asynchronously.

  3. Memory allocations in kernel_execve cause a page fault, bumping the
     MM reference counter:
       add_mm_counter_fast+0xb4/0xc0
       handle_mm_fault+0x6e4/0xea0
       __get_user_pages.part.78+0x190/0x37c
       __get_user_pages_remote+0x128/0x360
       get_arg_page+0x34/0xa0
       copy_string_kernel+0x194/0x2a4
       kernel_execve+0x11c/0x298
       call_usermodehelper_exec_async+0x114/0x194

  4. In case zero_pfn has not been initialized yet, zap_pte_range does
     not decrement the MM_ANONPAGES RSS counter and the BUG message is
     triggered shortly afterwards when __mmdrop checks the ref counters:
       __mmdrop+0x98/0x1d0
       free_bprm+0x44/0x118
       kernel_execve+0x160/0x1d8
       call_usermodehelper_exec_async+0x114/0x194
       ret_from_kernel_thread+0x14/0x1c

To avoid races such as described above, initialize init_zero_pfn at
early_initcall level.  Depending on the architecture, ZERO_PAGE is
either constant or gets initialized even earlier, at paging_init, so
there is no issue with initializing zero_pfn earlier.

Link: https://lkml.kernel.org/r/CALCv0x2YqOXEAy2Q=hafjhHCtTHVodChv1qpM=niAXOpqEbt7w@mail.gmail.com
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: stable@vger.kernel.org
Tested-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -149,7 +149,7 @@ static int __init init_zero_pfn(void)
 	zero_pfn = page_to_pfn(ZERO_PAGE(0));
 	return 0;
 }
-core_initcall(init_zero_pfn);
+early_initcall(init_zero_pfn);
 
 
 #if defined(SPLIT_RSS_COUNTING)



  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-05  8:53 [PATCH 4.14 00/52] 4.14.229-rc1 review Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 01/52] selinux: vsock: Set SID for socket returned by accept() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 02/52] ipv6: weaken the v4mapped source check Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 03/52] ext4: fix bh ref count on error paths Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 04/52] rpc: fix NULL dereference on kmalloc failure Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 05/52] ASoC: rt5640: Fix dac- and adc- vol-tlv values being off by a factor of 10 Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 06/52] ASoC: rt5651: " Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 07/52] ASoC: sgtl5000: set DAP_AVC_CTRL register to correct default value on probe Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 08/52] ASoC: es8316: Simplify adc_pga_gain_tlv table Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 09/52] ASoC: cs42l42: Fix mixer volume control Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 10/52] ASoC: cs42l42: Always wait at least 3ms after reset Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 11/52] powerpc: Force inlining of cpu_has_feature() to avoid build failure Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 12/52] vhost: Fix vhost_vq_reset() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 13/52] scsi: st: Fix a use after free in st_open() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 14/52] scsi: qla2xxx: Fix broken #endif placement Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 15/52] staging: comedi: cb_pcidas: fix request_irq() warn Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 16/52] staging: comedi: cb_pcidas64: " Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 17/52] ASoC: rt5659: Update MCLK rate in set_sysclk() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 18/52] ext4: do not iput inode under running transaction in ext4_rename() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 19/52] brcmfmac: clear EAP/association status bits on linkdown events Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 20/52] net: ethernet: aquantia: Handle error cleanup of start on open Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 21/52] appletalk: Fix skb allocation size in loopback case Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 22/52] net: wan/lmc: unregister device when no matching device is found Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 23/52] bpf: Remove MTU check in __bpf_skb_max_len Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 24/52] ALSA: usb-audio: Apply sample rate quirk to Logitech Connect Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 25/52] ALSA: hda/realtek: fix a determine_headset_type issue for a Dell AIO Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 26/52] ALSA: hda/realtek: call alc_update_headset_mode() in hp_automute_hook Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 27/52] tracing: Fix stack trace event size Greg Kroah-Hartman
2021-04-05  8:53 ` Greg Kroah-Hartman [this message]
2021-04-05  8:53 ` [PATCH 4.14 29/52] drm/amdgpu: fix offset calculation in amdgpu_vm_bo_clear_mappings() Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 30/52] drm/amdgpu: check alignment on CPU page for bo map Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 31/52] reiserfs: update reiserfs_xattrs_initialized() condition Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 32/52] mm: memcontrol: fix NR_WRITEBACK leak in memcg and system stats Greg Kroah-Hartman
2021-04-05  8:53 ` [PATCH 4.14 33/52] mm: memcg: make sure memory.events is uptodate when waking pollers Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 34/52] mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the same cacheline Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 35/52] mm: fix oom_kill event handling Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 36/52] mm: writeback: use exact memcg dirty counts Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 37/52] pinctrl: rockchip: fix restore error in resume Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 38/52] extcon: Add stubs for extcon_register_notifier_all() functions Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 39/52] extcon: Fix error handling in extcon_dev_register Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 40/52] firewire: nosy: Fix a use-after-free bug in nosy_ioctl() Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 41/52] usbip: vhci_hcd fix shift out-of-bounds in vhci_hub_control() Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 42/52] USB: quirks: ignore remote wake-up on Fibocom L850-GL LTE modem Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 43/52] usb: musb: Fix suspend with devices connected for a64 Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 44/52] usb: xhci-mtk: fix broken streams issue on 0.96 xHCI Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 45/52] cdc-acm: fix BREAK rx code path adding necessary calls Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 46/52] USB: cdc-acm: untangle a circular dependency between callback and softint Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 47/52] USB: cdc-acm: downgrade message to debug Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 48/52] USB: cdc-acm: fix use-after-free after probe failure Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 49/52] usb: gadget: udc: amd5536udc_pci fix null-ptr-dereference Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 50/52] staging: rtl8192e: Fix incorrect source in memcpy() Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 51/52] staging: rtl8192e: Change state information from u16 to u8 Greg Kroah-Hartman
2021-04-05  8:54 ` [PATCH 4.14 52/52] drivers: video: fbcon: fix NULL dereference in fbcon_cursor() Greg Kroah-Hartman
2021-04-05 17:57 ` [PATCH 4.14 00/52] 4.14.229-rc1 review Guenter Roeck
2021-04-06  7:14 ` Naresh Kamboju
2021-04-07  0:58 ` Samuel Zou

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210405085022.906274269@linuxfoundation.org \
    --to=gregkh@linuxfoundation.org \
    --cc=ebiederm@xmission.com \
    --cc=hughd@google.com \
    --cc=ilya.lipnitskiy@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    --cc=zhouyanjie@wanyeetech.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git