From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Muchun Song <smuchun@gmail.com>,
Mukesh Ojha <mojha@codeaurora.org>,
Prateek Sood <prsood@codeaurora.org>
Subject: [PATCH 4.4 21/56] driver core: Fix use-after-free and double free on glue directory
Date: Fri, 20 Sep 2019 00:04:02 +0200 [thread overview]
Message-ID: <20190919214754.417455135@linuxfoundation.org> (raw)
In-Reply-To: <20190919214742.483643642@linuxfoundation.org>
From: Muchun Song <smuchun@gmail.com>
commit ac43432cb1f5c2950408534987e57c2071e24d8f upstream.
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>
---
drivers/base/core.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -857,12 +857,63 @@ static inline struct kobject *get_glue_d
*/
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 = atomic_read(&glue_dir->kref.refcount);
+ if (!kobject_has_children(glue_dir) && !--ref)
kobject_del(glue_dir);
kobject_put(glue_dir);
mutex_unlock(&gdp_mutex);
next prev parent reply other threads:[~2019-09-19 22:22 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 22:03 [PATCH 4.4 00/56] 4.4.194-stable review Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 01/56] bridge/mdb: remove wrong use of NLM_F_MULTI Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 02/56] cdc_ether: fix rndis support for Mediatek based smartphones Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 03/56] ipv6: Fix the link time qualifier of ping_v6_proc_exit_net() Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 04/56] isdn/capi: check message length in capi_write() Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 05/56] net: Fix null de-reference of device refcount Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 06/56] sch_hhf: ensure quantum and hhf_non_hh_weight are non-zero Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 07/56] sctp: Fix the link time qualifier of sctp_ctrlsock_exit() Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 08/56] sctp: use transport pf_retrans in sctp_do_8_2_transport_strike Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 09/56] tcp: fix tcp_ecn_withdraw_cwr() to clear TCP_ECN_QUEUE_CWR Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 10/56] tipc: add NULL pointer check before calling kfree_rcu Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 11/56] tun: fix use-after-free when register netdev failed Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 12/56] Revert "MIPS: SiByte: Enable swiotlb for SWARM, LittleSur and BigSur" Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 13/56] Btrfs: fix assertion failure during fsync and use of stale transaction Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 14/56] genirq: Prevent NULL pointer dereference in resend_irqs() Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 15/56] KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 16/56] KVM: x86: work around leak of uninitialized stack contents Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 17/56] KVM: nVMX: handle page fault in vmread Greg Kroah-Hartman
2019-09-19 22:03 ` [PATCH 4.4 18/56] MIPS: VDSO: Prevent use of smp_processor_id() Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 19/56] MIPS: VDSO: Use same -m%-float cflag as the kernel proper Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 20/56] clk: rockchip: Dont yell about bad mmc phases when getting Greg Kroah-Hartman
2019-09-19 22:04 ` Greg Kroah-Hartman [this message]
2019-09-19 22:04 ` [PATCH 4.4 22/56] crypto: talitos - check AES key size Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 23/56] crypto: talitos - check data blocksize in ablkcipher Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 24/56] x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence GCC9 build warning Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 25/56] MIPS: netlogic: xlr: Remove erroneous check in nlm_fmn_send() Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 26/56] ARC: configs: Remove CONFIG_INITRAMFS_SOURCE from defconfigs Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 27/56] USB: usbcore: Fix slab-out-of-bounds bug during device reset Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 28/56] media: tm6000: double free if usb disconnect while streaming Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 29/56] x86/boot: Add missing bootparam that breaks boot on some platforms Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 30/56] xen-netfront: do not assume sk_buff_head list is empty in error handling Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 31/56] KVM: coalesced_mmio: add bounds checking Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 32/56] serial: sprd: correct the wrong sequence of arguments Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 33/56] tty/serial: atmel: reschedule TX after RX was started Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 34/56] mwifiex: Fix three heap overflow at parsing element in cfg80211_ap_settings Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 35/56] s390/bpf: fix lcgr instruction encoding Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 36/56] ARM: OMAP2+: Fix omap4 errata warning on other SoCs Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 37/56] s390/bpf: use 32-bit index for tail calls Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 38/56] NFSv4: Fix return values for nfs4_file_open() Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 39/56] NFS: Fix initialisation of I/O result struct in nfs_pgio_rpcsetup Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 40/56] Kconfig: Fix the reference to the IDT77105 Phy driver in the description of ATM_NICSTAR_USE_IDT77105 Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 41/56] ARM: 8874/1: mm: only adjust sections of valid mm structures Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 42/56] r8152: Set memory to all 0xFFs on failed reg reads Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 43/56] x86/apic: Fix arch_dynirq_lower_bound() bug for DT enabled machines Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 44/56] netfilter: nf_conntrack_ftp: Fix debug output Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 45/56] NFSv2: Fix eof handling Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 46/56] NFSv2: Fix write regression Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 47/56] cifs: set domainName when a domain-key is used in multiuser Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 48/56] cifs: Use kzfree() to zero out the password Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 49/56] sky2: Disable MSI on yet another ASUS boards (P6Xxxx) Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 50/56] tools/power turbostat: fix buffer overrun Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 51/56] net: seeq: Fix the function used to release some memory in an error handling path Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 52/56] dmaengine: ti: omap-dma: Add cleanup in omap_dma_probe() Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 53/56] keys: Fix missing null pointer check in request_key_auth_describe() Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 54/56] floppy: fix usercopy direction Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 55/56] media: technisat-usb2: break out of loop at end of buffer Greg Kroah-Hartman
2019-09-19 22:04 ` [PATCH 4.4 56/56] ARC: export "abort" for modules Greg Kroah-Hartman
2019-09-20 4:00 ` [PATCH 4.4 00/56] 4.4.194-stable review kernelci.org bot
2019-09-20 13:41 ` Guenter Roeck
2019-09-20 13:47 ` Jon Hunter
2019-09-20 14:35 ` Naresh Kamboju
2019-09-20 21:38 ` shuah
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