From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Dave Wysochanski <dwysocha@redhat.com>,
Ronnie Sahlberg <lsahlber@redhat.com>,
Pavel Shilovsky <pshilov@microsoft.com>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 17/34] cifs: Fix cifsInodeInfo lock_sem deadlock when reconnect occurs
Date: Fri, 8 Nov 2019 19:50:24 +0100 [thread overview]
Message-ID: <20191108174637.779336809@linuxfoundation.org> (raw)
In-Reply-To: <20191108174618.266472504@linuxfoundation.org>
From: Dave Wysochanski <dwysocha@redhat.com>
[ Upstream commit d46b0da7a33dd8c99d969834f682267a45444ab3 ]
There's a deadlock that is possible and can easily be seen with
a test where multiple readers open/read/close of the same file
and a disruption occurs causing reconnect. The deadlock is due
a reader thread inside cifs_strict_readv calling down_read and
obtaining lock_sem, and then after reconnect inside
cifs_reopen_file calling down_read a second time. If in
between the two down_read calls, a down_write comes from
another process, deadlock occurs.
CPU0 CPU1
---- ----
cifs_strict_readv()
down_read(&cifsi->lock_sem);
_cifsFileInfo_put
OR
cifs_new_fileinfo
down_write(&cifsi->lock_sem);
cifs_reopen_file()
down_read(&cifsi->lock_sem);
Fix the above by changing all down_write(lock_sem) calls to
down_write_trylock(lock_sem)/msleep() loop, which in turn
makes the second down_read call benign since it will never
block behind the writer while holding lock_sem.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Suggested-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed--by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/cifsglob.h | 5 +++++
fs/cifs/cifsproto.h | 1 +
fs/cifs/file.c | 23 +++++++++++++++--------
fs/cifs/smb2file.c | 2 +-
4 files changed, 22 insertions(+), 9 deletions(-)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 5367b684c1f74..7ae21ad420fbf 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1178,6 +1178,11 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file);
struct cifsInodeInfo {
bool can_cache_brlcks;
struct list_head llist; /* locks helb by this inode */
+ /*
+ * NOTE: Some code paths call down_read(lock_sem) twice, so
+ * we must always use use cifs_down_write() instead of down_write()
+ * for this semaphore to avoid deadlocks.
+ */
struct rw_semaphore lock_sem; /* protect the fields above */
/* BB add in lists for dirty pages i.e. write caching info for oplock */
struct list_head openFileList;
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index cd8025a249bba..cdf244df91c25 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -138,6 +138,7 @@ extern int cifs_unlock_range(struct cifsFileInfo *cfile,
struct file_lock *flock, const unsigned int xid);
extern int cifs_push_mandatory_locks(struct cifsFileInfo *cfile);
+extern void cifs_down_write(struct rw_semaphore *sem);
extern struct cifsFileInfo *cifs_new_fileinfo(struct cifs_fid *fid,
struct file *file,
struct tcon_link *tlink,
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 3504ef015493b..1c3f262d9c4d4 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -280,6 +280,13 @@ cifs_has_mand_locks(struct cifsInodeInfo *cinode)
return has_locks;
}
+void
+cifs_down_write(struct rw_semaphore *sem)
+{
+ while (!down_write_trylock(sem))
+ msleep(10);
+}
+
struct cifsFileInfo *
cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
struct tcon_link *tlink, __u32 oplock)
@@ -305,7 +312,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
INIT_LIST_HEAD(&fdlocks->locks);
fdlocks->cfile = cfile;
cfile->llist = fdlocks;
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
list_add(&fdlocks->llist, &cinode->llist);
up_write(&cinode->lock_sem);
@@ -457,7 +464,7 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler)
* Delete any outstanding lock records. We'll lose them when the file
* is closed anyway.
*/
- down_write(&cifsi->lock_sem);
+ cifs_down_write(&cifsi->lock_sem);
list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) {
list_del(&li->llist);
cifs_del_lock_waiters(li);
@@ -1011,7 +1018,7 @@ static void
cifs_lock_add(struct cifsFileInfo *cfile, struct cifsLockInfo *lock)
{
struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
list_add_tail(&lock->llist, &cfile->llist->locks);
up_write(&cinode->lock_sem);
}
@@ -1033,7 +1040,7 @@ cifs_lock_add_if(struct cifsFileInfo *cfile, struct cifsLockInfo *lock,
try_again:
exist = false;
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
exist = cifs_find_lock_conflict(cfile, lock->offset, lock->length,
lock->type, &conf_lock, CIFS_LOCK_OP);
@@ -1055,7 +1062,7 @@ cifs_lock_add_if(struct cifsFileInfo *cfile, struct cifsLockInfo *lock,
(lock->blist.next == &lock->blist));
if (!rc)
goto try_again;
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
list_del_init(&lock->blist);
}
@@ -1108,7 +1115,7 @@ cifs_posix_lock_set(struct file *file, struct file_lock *flock)
return rc;
try_again:
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
if (!cinode->can_cache_brlcks) {
up_write(&cinode->lock_sem);
return rc;
@@ -1312,7 +1319,7 @@ cifs_push_locks(struct cifsFileInfo *cfile)
int rc = 0;
/* we are going to update can_cache_brlcks here - need a write access */
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
if (!cinode->can_cache_brlcks) {
up_write(&cinode->lock_sem);
return rc;
@@ -1501,7 +1508,7 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock,
if (!buf)
return -ENOMEM;
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
for (i = 0; i < 2; i++) {
cur = buf;
num = 0;
diff --git a/fs/cifs/smb2file.c b/fs/cifs/smb2file.c
index dee5250701deb..41f1a5dd33a53 100644
--- a/fs/cifs/smb2file.c
+++ b/fs/cifs/smb2file.c
@@ -138,7 +138,7 @@ smb2_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock,
cur = buf;
- down_write(&cinode->lock_sem);
+ cifs_down_write(&cinode->lock_sem);
list_for_each_entry_safe(li, tmp, &cfile->llist->locks, llist) {
if (flock->fl_start > li->offset ||
(flock->fl_start + length) <
--
2.20.1
next prev parent reply other threads:[~2019-11-08 18:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 18:50 [PATCH 4.9 00/34] 4.9.200-stable review Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 01/34] regulator: ti-abb: Fix timeout in ti_abb_wait_txdone/ti_abb_clear_all_txdone Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 02/34] regulator: pfuze100-regulator: Variable "val" in pfuze100_regulator_probe() could be uninitialized Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 03/34] ASoC: wm_adsp: Dont generate kcontrols without READ flags Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 04/34] ASoc: rockchip: i2s: Fix RPM imbalance Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 05/34] ARM: dts: logicpd-torpedo-som: Remove twl_keypad Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 06/34] pinctrl: ns2: Fix off by one bugs in ns2_pinmux_enable() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 07/34] ARM: mm: fix alignment handler faults under memory pressure Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 08/34] scsi: scsi_dh_alua: handle RTPG sense code correctly during state transitions Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 09/34] scsi: sni_53c710: fix compilation error Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 10/34] scsi: fix kconfig dependency warning related to 53C700_LE_ON_BE Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 11/34] ARM: dts: imx7s: Correct GPTs ipg clock source Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 12/34] perf kmem: Fix memory leak in compact_gfp_flags() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 13/34] ARM: davinci: dm365: Fix McBSP dma_slave_map entry Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 14/34] scsi: target: core: Do not overwrite CDB byte 1 Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 15/34] of: unittest: fix memory leak in unittest_data_add Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 16/34] MIPS: bmips: mark exception vectors as char arrays Greg Kroah-Hartman
2019-11-08 18:50 ` Greg Kroah-Hartman [this message]
2019-11-08 18:50 ` [PATCH 4.9 18/34] dccp: do not leak jiffies on the wire Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 19/34] net: fix sk_page_frag() recursion from memory reclaim Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 20/34] net: hisilicon: Fix ping latency when deal with high throughput Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 21/34] net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 22/34] selftests: net: reuseport_dualstack: fix uninitalized parameter Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 23/34] net: add READ_ONCE() annotation in __skb_wait_for_more_packets() Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 24/34] net: dsa: fix switch tree list Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 25/34] net: bcmgenet: reset 40nm EPHY on energy detect Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 26/34] vxlan: check tun_info options_len properly Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 27/34] net/mlx4_core: Dynamically set guaranteed amount of counters per VF Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 28/34] inet: stop leaking jiffies on the wire Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 29/34] Kbuild: make designated_init attribute fatal Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 30/34] kbuild: use -fmacro-prefix-map to make __FILE__ a relative path Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 31/34] kbuild: add -fcf-protection=none when using retpoline flags Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 32/34] net/flow_dissector: switch to siphash Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 33/34] dmaengine: qcom: bam_dma: Fix resource leak Greg Kroah-Hartman
2019-11-08 18:50 ` [PATCH 4.9 34/34] alarmtimer: Change remaining ENOTSUPP to EOPNOTSUPP Greg Kroah-Hartman
2019-11-09 0:57 ` [PATCH 4.9 00/34] 4.9.200-stable review kernelci.org bot
2019-11-09 10:18 ` Naresh Kamboju
2019-11-09 15:39 ` Guenter Roeck
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