From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Lei Xue <carmark.dlut@gmail.com>,
Dave Wysochanski <dwysocha@redhat.com>,
David Howells <dhowells@redhat.com>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 10/48] cachefiles: Fix race between read_waiter and read_copier involving op->to_do
Date: Mon, 1 Jun 2020 19:53:20 +0200 [thread overview]
Message-ID: <20200601173955.269444801@linuxfoundation.org> (raw)
In-Reply-To: <20200601173952.175939894@linuxfoundation.org>
From: Lei Xue <carmark.dlut@gmail.com>
[ Upstream commit 7bb0c5338436dae953622470d52689265867f032 ]
There is a potential race in fscache operation enqueuing for reading and
copying multiple pages from cachefiles to netfs. The problem can be seen
easily on a heavy loaded system (for example many processes reading files
continually on an NFS share covered by fscache triggered this problem within
a few minutes).
The race is due to cachefiles_read_waiter() adding the op to the monitor
to_do list and then then drop the object->work_lock spinlock before
completing fscache_enqueue_operation(). Once the lock is dropped,
cachefiles_read_copier() grabs the op, completes processing it, and
makes it through fscache_retrieval_complete() which sets the op->state to
the final state of FSCACHE_OP_ST_COMPLETE(4). When cachefiles_read_waiter()
finally gets through the remainder of fscache_enqueue_operation()
it sees the invalid state, and hits the ASSERTCMP and the following
oops is seen:
[ 2259.612361] FS-Cache:
[ 2259.614785] FS-Cache: Assertion failed
[ 2259.618639] FS-Cache: 4 == 5 is false
[ 2259.622456] ------------[ cut here ]------------
[ 2259.627190] kernel BUG at fs/fscache/operation.c:70!
...
[ 2259.791675] RIP: 0010:[<ffffffffc061b4cf>] [<ffffffffc061b4cf>] fscache_enqueue_operation+0xff/0x170 [fscache]
[ 2259.802059] RSP: 0000:ffffa0263d543be0 EFLAGS: 00010046
[ 2259.807521] RAX: 0000000000000019 RBX: ffffa01a4d390480 RCX: 0000000000000006
[ 2259.814847] RDX: 0000000000000000 RSI: 0000000000000046 RDI: ffffa0263d553890
[ 2259.822176] RBP: ffffa0263d543be8 R08: 0000000000000000 R09: ffffa0263c2d8708
[ 2259.829502] R10: 0000000000001e7f R11: 0000000000000000 R12: ffffa01a4d390480
[ 2259.844483] R13: ffff9fa9546c5920 R14: ffffa0263d543c80 R15: ffffa0293ff9bf10
[ 2259.859554] FS: 00007f4b6efbd700(0000) GS:ffffa0263d540000(0000) knlGS:0000000000000000
[ 2259.875571] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2259.889117] CR2: 00007f49e1624ff0 CR3: 0000012b38b38000 CR4: 00000000007607e0
[ 2259.904015] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2259.918764] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 2259.933449] PKRU: 55555554
[ 2259.943654] Call Trace:
[ 2259.953592] <IRQ>
[ 2259.955577] [<ffffffffc03a7c12>] cachefiles_read_waiter+0x92/0xf0 [cachefiles]
[ 2259.978039] [<ffffffffa34d3942>] __wake_up_common+0x82/0x120
[ 2259.991392] [<ffffffffa34d3a63>] __wake_up_common_lock+0x83/0xc0
[ 2260.004930] [<ffffffffa34d3510>] ? task_rq_unlock+0x20/0x20
[ 2260.017863] [<ffffffffa34d3ab3>] __wake_up+0x13/0x20
[ 2260.030230] [<ffffffffa34c72a0>] __wake_up_bit+0x50/0x70
[ 2260.042535] [<ffffffffa35bdcdb>] unlock_page+0x2b/0x30
[ 2260.054495] [<ffffffffa35bdd09>] page_endio+0x29/0x90
[ 2260.066184] [<ffffffffa368fc81>] mpage_end_io+0x51/0x80
CPU1
cachefiles_read_waiter()
20 static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
21 int sync, void *_key)
22 {
...
61 spin_lock(&object->work_lock);
62 list_add_tail(&monitor->op_link, &op->to_do);
63 spin_unlock(&object->work_lock);
<begin race window>
64
65 fscache_enqueue_retrieval(op);
182 static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
183 {
184 fscache_enqueue_operation(&op->op);
185 }
58 void fscache_enqueue_operation(struct fscache_operation *op)
59 {
60 struct fscache_cookie *cookie = op->object->cookie;
61
62 _enter("{OBJ%x OP%x,%u}",
63 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
64
65 ASSERT(list_empty(&op->pend_link));
66 ASSERT(op->processor != NULL);
67 ASSERT(fscache_object_is_available(op->object));
68 ASSERTCMP(atomic_read(&op->usage), >, 0);
<end race window>
CPU2
cachefiles_read_copier()
168 while (!list_empty(&op->to_do)) {
...
202 fscache_end_io(op, monitor->netfs_page, error);
203 put_page(monitor->netfs_page);
204 fscache_retrieval_complete(op, 1);
CPU1
58 void fscache_enqueue_operation(struct fscache_operation *op)
59 {
...
69 ASSERTIFCMP(op->state != FSCACHE_OP_ST_IN_PROGRESS,
70 op->state, ==, FSCACHE_OP_ST_CANCELLED);
Signed-off-by: Lei Xue <carmark.dlut@gmail.com>
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cachefiles/rdwr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index c05ab2ec0fef..5df898fd0a0a 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -64,9 +64,9 @@ static int cachefiles_read_waiter(wait_queue_t *wait, unsigned mode,
object = container_of(op->op.object, struct cachefiles_object, fscache);
spin_lock(&object->work_lock);
list_add_tail(&monitor->op_link, &op->to_do);
+ fscache_enqueue_retrieval(op);
spin_unlock(&object->work_lock);
- fscache_enqueue_retrieval(op);
fscache_put_retrieval(op);
return 0;
}
--
2.25.1
next prev parent reply other threads:[~2020-06-01 19:01 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-01 17:53 [PATCH 4.4 00/48] 4.4.226-rc1 review Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 01/48] ax25: fix setsockopt(SO_BINDTODEVICE) Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 02/48] net: revert "net: get rid of an signed integer overflow in ip_idents_reserve()" Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 03/48] sctp: Start shutdown on association restart if in SHUTDOWN-SENT state and socket is closed Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 04/48] net/mlx5: Add command entry handling completion Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 05/48] net: sun: fix missing release regions in cas_init_one() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 06/48] net/mlx4_core: fix a memory leak bug Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 07/48] uapi: fix linux/if_pppol2tp.h userspace compilation errors Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 08/48] IB/cma: Fix reference count leak when no ipv4 addresses are set Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 09/48] gfs2: dont call quota_unhold if quotas are not locked Greg Kroah-Hartman
2020-06-01 17:53 ` Greg Kroah-Hartman [this message]
2020-06-01 17:53 ` [PATCH 4.4 11/48] usb: gadget: legacy: fix redundant initialization warnings Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 12/48] cifs: Fix null pointer check in cifs_read Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 13/48] Input: usbtouchscreen - add support for BonXeon TP Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 14/48] Input: i8042 - add ThinkPad S230u to i8042 nomux list Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 15/48] Input: evdev - call input_flush_device() on release(), not flush() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 16/48] Input: xpad - add custom init packet for Xbox One S controllers Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 17/48] Input: i8042 - add ThinkPad S230u to i8042 reset list Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 18/48] IB/qib: Call kobject_put() when kobject_init_and_add() fails Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 19/48] ALSA: hwdep: fix a left shifting 1 by 31 UB bug Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 20/48] ALSA: usb-audio: mixer: volume quirk for ESS Technology Asus USB DAC Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 21/48] exec: Always set cap_ambient in cap_bprm_set_creds Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 22/48] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 23/48] include/asm-generic/topology.h: guard cpumask_of_node() macro argument Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 24/48] iommu: Fix reference count leak in iommu_group_alloc Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 25/48] parisc: Fix kernel panic in mem_init() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 26/48] x86/dma: Fix max PFN arithmetic overflow on 32 bit systems Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 27/48] xfrm: allow to accept packets with ipv6 NEXTHDR_HOP in xfrm_input Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 28/48] xfrm: fix a warning in xfrm_policy_insert_list Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 29/48] xfrm: fix a NULL-ptr deref in xfrm_local_error Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 30/48] vti4: eliminated some duplicate code Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 31/48] ip_vti: receive ipip packet by calling ip_tunnel_rcv Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 32/48] netfilter: nft_reject_bridge: enable reject with bridge vlan Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 33/48] netfilter: ipset: Fix subcounter update skip Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 34/48] netfilter: nf_conntrack_pptp: prevent buffer overflows in debug code Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 35/48] qlcnic: fix missing release in qlcnic_83xx_interrupt_test Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 36/48] bonding: Fix reference count leak in bond_sysfs_slave_add Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 37/48] Revert "Input: i8042 - add ThinkPad S230u to i8042 nomux list" Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 38/48] netfilter: nf_conntrack_pptp: fix compilation warning with W=1 build Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 39/48] mm: remove VM_BUG_ON(PageSlab()) from page_mapcount() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 40/48] drm/fb-helper: Use proper plane mask for fb cleanup Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 41/48] genirq/generic_pending: Do not lose pending affinity update Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 42/48] usb: renesas_usbhs: gadget: fix spin_lock_init() for &uep->lock Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 43/48] mac80211: fix memory leak Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 44/48] net: rtnl_configure_link: fix dev flags changes arg to __dev_notify_flags Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 45/48] mm/vmalloc.c: dont dereference possible NULL pointer in __vunmap() Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 46/48] asm-prototypes: Clear any CPP defines before declaring the functions Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 47/48] sc16is7xx: move label err_spi to correct section Greg Kroah-Hartman
2020-06-01 17:53 ` [PATCH 4.4 48/48] drm/msm: Fix possible null dereference on failure of get_pages() Greg Kroah-Hartman
2020-06-01 22:14 ` [PATCH 4.4 00/48] 4.4.226-rc1 review Chris Paterson
2020-06-02 2:06 ` Sasha Levin
2020-06-02 9:07 ` Chris Paterson
2020-06-02 10:24 ` Greg Kroah-Hartman
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