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 4.9 22/35] mm: fix race by making init_zero_pfn() early_initcall
Date: Mon, 5 Apr 2021 10:53:57 +0200 [thread overview]
Message-ID: <20210405085019.580637824@linuxfoundation.org> (raw)
In-Reply-To: <20210405085018.871387942@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
@@ -132,7 +132,7 @@ 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)
next prev parent reply other threads:[~2021-04-05 8:57 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-05 8:53 [PATCH 4.9 00/35] 4.9.265-rc1 review Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 01/35] selinux: vsock: Set SID for socket returned by accept() Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 02/35] ipv6: weaken the v4mapped source check Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 03/35] ext4: fix bh ref count on error paths Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 04/35] rpc: fix NULL dereference on kmalloc failure Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 05/35] 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 4.9 06/35] ASoC: rt5651: " Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 07/35] ASoC: sgtl5000: set DAP_AVC_CTRL register to correct default value on probe Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 08/35] powerpc: Force inlining of cpu_has_feature() to avoid build failure Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 09/35] vhost: Fix vhost_vq_reset() Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 10/35] scsi: st: Fix a use after free in st_open() Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 11/35] scsi: qla2xxx: Fix broken #endif placement Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 12/35] staging: comedi: cb_pcidas: fix request_irq() warn Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 13/35] staging: comedi: cb_pcidas64: " Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 14/35] ASoC: rt5659: Update MCLK rate in set_sysclk() Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 15/35] ext4: do not iput inode under running transaction in ext4_rename() Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 16/35] appletalk: Fix skb allocation size in loopback case Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 17/35] net: wan/lmc: unregister device when no matching device is found Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 18/35] bpf: Remove MTU check in __bpf_skb_max_len Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 19/35] ALSA: usb-audio: Apply sample rate quirk to Logitech Connect Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 20/35] ALSA: hda/realtek: call alc_update_headset_mode() in hp_automute_hook Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 21/35] 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 4.9 23/35] reiserfs: update reiserfs_xattrs_initialized() condition Greg Kroah-Hartman
2021-04-05 8:53 ` [PATCH 4.9 24/35] pinctrl: rockchip: fix restore error in resume Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 25/35] extcon: Fix error handling in extcon_dev_register Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 26/35] firewire: nosy: Fix a use-after-free bug in nosy_ioctl() Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 27/35] USB: quirks: ignore remote wake-up on Fibocom L850-GL LTE modem Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 28/35] usb: xhci-mtk: fix broken streams issue on 0.96 xHCI Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 29/35] cdc-acm: fix BREAK rx code path adding necessary calls Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 30/35] USB: cdc-acm: downgrade message to debug Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 31/35] USB: cdc-acm: fix use-after-free after probe failure Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 32/35] staging: rtl8192e: Fix incorrect source in memcpy() Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 33/35] staging: rtl8192e: Change state information from u16 to u8 Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 34/35] audit: fix a net reference leak in audit_send_reply() Greg Kroah-Hartman
2021-04-05 8:54 ` [PATCH 4.9 35/35] audit: fix a net reference leak in audit_list_rules_send() Greg Kroah-Hartman
2021-04-05 17:27 ` [PATCH 4.9 00/35] 4.9.265-rc1 review Florian Fainelli
2021-04-05 17:56 ` Guenter Roeck
2021-04-05 23:51 ` Guenter Roeck
2021-04-06 2:22 ` Guenter Roeck
2021-04-06 2:36 ` Guenter Roeck
2021-04-07 10:18 ` Greg Kroah-Hartman
2021-04-06 0:29 ` Shuah Khan
2021-04-06 7:40 ` Naresh Kamboju
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