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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Muchun Song <smuchun@gmail.com>,
	Mukesh Ojha <mojha@codeaurora.org>,
	Prateek Sood <prsood@codeaurora.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.19 31/68] driver core: Fix use-after-free and double free on glue directory
Date: Tue, 13 Aug 2019 22:15:09 -0400
Message-ID: <20190814021548.16001-31-sashal@kernel.org> (raw)
In-Reply-To: <20190814021548.16001-1-sashal@kernel.org>

From: Muchun Song <smuchun@gmail.com>

[ Upstream commit ac43432cb1f5c2950408534987e57c2071e24d8f ]

There is a race condition between removing glue directory and adding a new
device under the glue dir. It can be reproduced in following test:

CPU1:                                         CPU2:

device_add()
  get_device_parent()
    class_dir_create_and_add()
      kobject_add_internal()
        create_dir()    // create glue_dir

                                              device_add()
                                                get_device_parent()
                                                  kobject_get() // get glue_dir

device_del()
  cleanup_glue_dir()
    kobject_del(glue_dir)

                                                kobject_add()
                                                  kobject_add_internal()
                                                    create_dir() // in glue_dir
                                                      sysfs_create_dir_ns()
                                                        kernfs_create_dir_ns(sd)

      sysfs_remove_dir() // glue_dir->sd=NULL
      sysfs_put()        // free glue_dir->sd

                                                          // sd is freed
                                                          kernfs_new_node(sd)
                                                            kernfs_get(glue_dir)
                                                            kernfs_add_one()
                                                            kernfs_put()

Before CPU1 remove last child device under glue dir, if CPU2 add a new
device under glue dir, the glue_dir kobject reference count will be
increase to 2 via kobject_get() in get_device_parent(). And CPU2 has
been called kernfs_create_dir_ns(), but not call kernfs_new_node().
Meanwhile, CPU1 call sysfs_remove_dir() and sysfs_put(). This result in
glue_dir->sd is freed and it's reference count will be 0. Then CPU2 call
kernfs_get(glue_dir) will trigger a warning in kernfs_get() and increase
it's reference count to 1. Because glue_dir->sd is freed by CPU1, the next
call kernfs_add_one() by CPU2 will fail(This is also use-after-free)
and call kernfs_put() to decrease reference count. Because the reference
count is decremented to 0, it will also call kmem_cache_free() to free
the glue_dir->sd again. This will result in double free.

In order to avoid this happening, we also should make sure that kernfs_node
for glue_dir is released in CPU1 only when refcount for glue_dir kobj is
1 to fix this race.

The following calltrace is captured in kernel 4.14 with the following patch
applied:

commit 726e41097920 ("drivers: core: Remove glue dirs from sysfs earlier")

--------------------------------------------------------------------------
[    3.633703] WARNING: CPU: 4 PID: 513 at .../fs/kernfs/dir.c:494
                Here is WARN_ON(!atomic_read(&kn->count) in kernfs_get().
....
[    3.633986] Call trace:
[    3.633991]  kernfs_create_dir_ns+0xa8/0xb0
[    3.633994]  sysfs_create_dir_ns+0x54/0xe8
[    3.634001]  kobject_add_internal+0x22c/0x3f0
[    3.634005]  kobject_add+0xe4/0x118
[    3.634011]  device_add+0x200/0x870
[    3.634017]  _request_firmware+0x958/0xc38
[    3.634020]  request_firmware_into_buf+0x4c/0x70
....
[    3.634064] kernel BUG at .../mm/slub.c:294!
                Here is BUG_ON(object == fp) in set_freepointer().
....
[    3.634346] Call trace:
[    3.634351]  kmem_cache_free+0x504/0x6b8
[    3.634355]  kernfs_put+0x14c/0x1d8
[    3.634359]  kernfs_create_dir_ns+0x88/0xb0
[    3.634362]  sysfs_create_dir_ns+0x54/0xe8
[    3.634366]  kobject_add_internal+0x22c/0x3f0
[    3.634370]  kobject_add+0xe4/0x118
[    3.634374]  device_add+0x200/0x870
[    3.634378]  _request_firmware+0x958/0xc38
[    3.634381]  request_firmware_into_buf+0x4c/0x70
--------------------------------------------------------------------------

Fixes: 726e41097920 ("drivers: core: Remove glue dirs from sysfs earlier")
Signed-off-by: Muchun Song <smuchun@gmail.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Link: https://lore.kernel.org/r/20190727032122.24639-1-smuchun@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/base/core.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index e1a8d5c06f65e..fcda6313e7def 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1648,12 +1648,63 @@ static inline struct kobject *get_glue_dir(struct device *dev)
  */
 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
 {
+	unsigned int ref;
+
 	/* see if we live in a "glue" directory */
 	if (!live_in_glue_dir(glue_dir, dev))
 		return;
 
 	mutex_lock(&gdp_mutex);
-	if (!kobject_has_children(glue_dir))
+	/**
+	 * There is a race condition between removing glue directory
+	 * and adding a new device under the glue directory.
+	 *
+	 * CPU1:                                         CPU2:
+	 *
+	 * device_add()
+	 *   get_device_parent()
+	 *     class_dir_create_and_add()
+	 *       kobject_add_internal()
+	 *         create_dir()    // create glue_dir
+	 *
+	 *                                               device_add()
+	 *                                                 get_device_parent()
+	 *                                                   kobject_get() // get glue_dir
+	 *
+	 * device_del()
+	 *   cleanup_glue_dir()
+	 *     kobject_del(glue_dir)
+	 *
+	 *                                               kobject_add()
+	 *                                                 kobject_add_internal()
+	 *                                                   create_dir() // in glue_dir
+	 *                                                     sysfs_create_dir_ns()
+	 *                                                       kernfs_create_dir_ns(sd)
+	 *
+	 *       sysfs_remove_dir() // glue_dir->sd=NULL
+	 *       sysfs_put()        // free glue_dir->sd
+	 *
+	 *                                                         // sd is freed
+	 *                                                         kernfs_new_node(sd)
+	 *                                                           kernfs_get(glue_dir)
+	 *                                                           kernfs_add_one()
+	 *                                                           kernfs_put()
+	 *
+	 * Before CPU1 remove last child device under glue dir, if CPU2 add
+	 * a new device under glue dir, the glue_dir kobject reference count
+	 * will be increase to 2 in kobject_get(k). And CPU2 has been called
+	 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
+	 * and sysfs_put(). This result in glue_dir->sd is freed.
+	 *
+	 * Then the CPU2 will see a stale "empty" but still potentially used
+	 * glue dir around in kernfs_new_node().
+	 *
+	 * In order to avoid this happening, we also should make sure that
+	 * kernfs_node for glue_dir is released in CPU1 only when refcount
+	 * for glue_dir kobj is 1.
+	 */
+	ref = kref_read(&glue_dir->kref);
+	if (!kobject_has_children(glue_dir) && !--ref)
 		kobject_del(glue_dir);
 	kobject_put(glue_dir);
 	mutex_unlock(&gdp_mutex);
-- 
2.20.1


  parent reply index

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-14  2:14 [PATCH AUTOSEL 4.19 01/68] iio: adc: max9611: Fix misuse of GENMASK macro Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 02/68] iio: cros_ec_accel_legacy: Fix incorrect channel setting Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 03/68] HID: Add 044f:b320 ThrustMaster, Inc. 2 in 1 DT Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 04/68] MIPS: kernel: only use i8253 clocksource with periodic clockevent Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 05/68] mips: fix cacheinfo Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 06/68] netfilter: ebtables: fix a memory leak bug in compat Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 07/68] ASoC: dapm: Fix handling of custom_stop_condition on DAPM graph walks Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 08/68] selftests/bpf: fix sendmsg6_prog on s390 Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 09/68] bonding: Force slave speed check after link state recovery for 802.3ad Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 10/68] net: mvpp2: Don't check for 3 consecutive Idle frames for 10G links Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 11/68] selftests: forwarding: gre_multipath: Enable IPv4 forwarding Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 12/68] selftests: forwarding: gre_multipath: Fix flower filters Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 13/68] can: dev: call netif_carrier_off() in register_candev() Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 14/68] can: mcp251x: add error check when wq alloc failed Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 15/68] can: gw: Fix error path of cgw_module_init Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 16/68] ASoC: Fail card instantiation if DAI format setup fails Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 17/68] st21nfca_connectivity_event_received: null check the allocation Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 18/68] st_nci_hci_connectivity_event_received: " Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 19/68] ASoC: rockchip: Fix mono capture Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 20/68] ASoC: ti: davinci-mcasp: Correct slot_width posed constraint Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 21/68] net: usb: qmi_wwan: Add the BroadMobi BM818 card Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 22/68] qed: RDMA - Fix the hw_ver returned in device attributes Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 23/68] isdn: mISDN: hfcsusb: Fix possible null-pointer dereferences in start_isoc_chain() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 24/68] mac80211_hwsim: Fix possible null-pointer dereferences in hwsim_dump_radio_nl() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 25/68] netfilter: ipset: Actually allow destination MAC address for hash:ip,mac sets too Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 26/68] netfilter: ipset: Copy the right MAC address in bitmap:ip,mac and hash:ip,mac sets Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 27/68] netfilter: ipset: Fix rename concurrency with listing Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 28/68] netfilter: ebtables: also count base chain policies Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 29/68] rxrpc: Fix potential deadlock Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 30/68] rxrpc: Fix the lack of notification when sendmsg() fails on a DATA packet Sasha Levin
2019-08-14  2:15 ` Sasha Levin [this message]
2019-08-14  7:36   ` [PATCH AUTOSEL 4.19 31/68] driver core: Fix use-after-free and double free on glue directory Greg Kroah-Hartman
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 32/68] isdn: hfcsusb: Fix mISDN driver crash caused by transfer buffer on the stack Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 33/68] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 34/68] perf bench numa: Fix cpu0 binding Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 35/68] Input: kbtab - sanity check for endpoint type Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 36/68] net: usb: pegasus: fix improper read if get_registers() fail Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 37/68] can: sja1000: force the string buffer NULL-terminated Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 38/68] can: peak_usb: " Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 39/68] net/ethernet/qlogic/qed: " Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 40/68] NFSv4: Fix a potential sleep while atomic in nfs4_do_reclaim() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 41/68] NFS: Fix regression whereby fscache errors are appearing on 'nofsc' mounts Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 42/68] HID: quirks: Set the INCREMENT_USAGE_ON_DUPLICATE quirk on Saitek X52 Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 43/68] HID: holtek: test for sanity of intfdata Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 44/68] HID: input: fix a4tech horizontal wheel custom usage Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 45/68] drm/rockchip: Suspend DP late Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 46/68] SMB3: Fix potential memory leak when processing compound chain Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 47/68] SMB3: Kernel oops mounting a encryptData share with CONFIG_DEBUG_VIRTUAL Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 48/68] HID: hiddev: avoid opening a disconnected device Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 49/68] HID: hiddev: do cleanup in failure of opening a device Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 50/68] s390: put _stext and _etext into .text section Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 51/68] Input: iforce - add sanity checks Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 52/68] net: cxgb3_main: Fix a resource leak in a error path in 'init_one()' Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 53/68] net: stmmac: Fix issues when number of Queues >= 4 Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 54/68] net: stmmac: tc: Do not return a fragment entry Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 55/68] net: hisilicon: make hip04_tx_reclaim non-reentrant Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 56/68] net: hisilicon: fix hip04-xmit never return TX_BUSY Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 57/68] net: hisilicon: Fix dma_map_single failed on arm64 Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 58/68] libata: have ata_scsi_rw_xlat() fail invalid passthrough requests Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 59/68] libata: add SG safety checks in SFF pio transfers Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 60/68] x86/lib/cpu: Address missing prototypes warning Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 61/68] drm/vmwgfx: fix memory leak when too many retries have occurred Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 62/68] block, bfq: handle NULL return value by bfq_init_rq() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 63/68] perf ftrace: Fix failure to set cpumask when only one cpu is present Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 64/68] perf cpumap: Fix writing to illegal memory in handling cpumap mask Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 65/68] perf pmu-events: Fix missing "cpu_clk_unhalted.core" event Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 66/68] KVM: arm64: Don't write junk to sysregs on reset Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 67/68] KVM: arm: Don't write junk to CP15 registers " Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 68/68] selftests: kvm: Adding config fragments Sasha Levin

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