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Groups > linux.kernel > #1572660

[PATCH 4.9 28/51] af_unix: move unix_mknod() out of bindlock

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.9 28/51] af_unix: move unix_mknod() out of bindlock
Date 2017-02-02 19:50 +0100
Message-ID <t6uCg-7FA-79@gated-at.bofh.it> (permalink)
References <t6usx-7Bs-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: WANG Cong <xiyou.wangcong@gmail.com>


[ Upstream commit 0fb44559ffd67de8517098b81f675fa0210f13f0 ]

Dmitry reported a deadlock scenario:

unix_bind() path:
u->bindlock ==> sb_writer

do_splice() path:
sb_writer ==> pipe->mutex ==> u->bindlock

In the unix_bind() code path, unix_mknod() does not have to
be done with u->bindlock held, since it is a pure fs operation,
so we can just move unix_mknod() out.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/unix/af_unix.c |   27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -995,6 +995,7 @@ static int unix_bind(struct socket *sock
 	unsigned int hash;
 	struct unix_address *addr;
 	struct hlist_head *list;
+	struct path path = { NULL, NULL };
 
 	err = -EINVAL;
 	if (sunaddr->sun_family != AF_UNIX)
@@ -1010,9 +1011,20 @@ static int unix_bind(struct socket *sock
 		goto out;
 	addr_len = err;
 
+	if (sun_path[0]) {
+		umode_t mode = S_IFSOCK |
+		       (SOCK_INODE(sock)->i_mode & ~current_umask());
+		err = unix_mknod(sun_path, mode, &path);
+		if (err) {
+			if (err == -EEXIST)
+				err = -EADDRINUSE;
+			goto out;
+		}
+	}
+
 	err = mutex_lock_interruptible(&u->bindlock);
 	if (err)
-		goto out;
+		goto out_put;
 
 	err = -EINVAL;
 	if (u->addr)
@@ -1029,16 +1041,6 @@ static int unix_bind(struct socket *sock
 	atomic_set(&addr->refcnt, 1);
 
 	if (sun_path[0]) {
-		struct path path;
-		umode_t mode = S_IFSOCK |
-		       (SOCK_INODE(sock)->i_mode & ~current_umask());
-		err = unix_mknod(sun_path, mode, &path);
-		if (err) {
-			if (err == -EEXIST)
-				err = -EADDRINUSE;
-			unix_release_addr(addr);
-			goto out_up;
-		}
 		addr->hash = UNIX_HASH_SIZE;
 		hash = d_real_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE - 1);
 		spin_lock(&unix_table_lock);
@@ -1065,6 +1067,9 @@ out_unlock:
 	spin_unlock(&unix_table_lock);
 out_up:
 	mutex_unlock(&u->bindlock);
+out_put:
+	if (err)
+		path_put(&path);
 out:
 	return err;
 }

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Thread

[PATCH 4.9 00/51] 4.9.8-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 35/51] xfs: adjust allocation length in xfs_alloc_space_available Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 36/51] xfs: dont rely on ->total in xfs_alloc_space_available Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 09/51] tcp: fix tcp_fastopen unaligned access complaints on sparc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 05/51] mlxsw: pci: Fix EQE structure definition Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 04/51] mlxsw: switchx2: Fix memory leak at skb reallocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 03/51] mlxsw: spectrum: Fix memory leak at skb reallocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 26/51] net: mpls: Fix multipath selection for LSR use case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:40 +0100
  [PATCH 4.9 11/51] mlx4: do not call napi_schedule() without care Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 14/51] ax25: Fix segfault after sock connection timeout Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 47/51] xfs: verify dirblocklog correctly Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 43/51] xfs: sanity check inode di_mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 39/51] xfs: sanity check directory inode di_size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 15/51] net sched actions: fix refcnt when GETing of action after bind Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 50/51] xfs: clear _XBF_PAGES from buffers when readahead page Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 22/51] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 31/51] lwtunnel: Fix oops on state free after encap module unload Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 23/51] tcp: initialize max window for a new fastopen socket Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 49/51] xfs: extsize hints are not unlikely in xfs_bmap_btalloc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 24/51] net/mlx5e: Do not recycle pages from emergency reserve Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 08/51] net: systemport: Decouple flow control from __bcm_sysport_tx_reclaim Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 30/51] net: Specify the owning module for lwtunnel ops Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 20/51] net: phy: bcm63xx: Utilize correct config_intr function Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 27/51] r8152: dont execute runtime suspend if the tx is not empty Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 46/51] xfs: fix COW writeback race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 44/51] xfs: dont wrap ID in xfs_dq_get_next_id Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 06/51] net: lwtunnel: Handle lwtunnel_fill_encap failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 42/51] xfs: sanity check inode mode when creating new dentry Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 32/51] net: dsa: Bring back device detaching in dsa_slave_suspend() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 41/51] xfs: replace xfs_mode_to_ftype table with switch statement Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 10/51] openvswitch: maintain correct checksum state in conntrack actions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 13/51] ip6_tunnel: Account for tunnel header in tunnel MTU Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 45/51] xfs: fix xfs_mode_to_ftype() prototype Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 28/51] af_unix: move unix_mknod() out of bindlock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 25/51] bridge: netlink: call br_changelink() during br_dev_newlink() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 34/51] xfs: fix bogus minleft manipulations Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 37/51] xfs: dont print warnings when xfs_log_force fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 48/51] xfs: remove racy hasattr check from attr ops Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 12/51] ravb: do not use zero-length alignment DMA descriptor Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 51/51] xfs: fix bmv_count confusion w/ shared extents Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 33/51] xfs: bump up reserved blocks in xfs_alloc_set_aside Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 19:50 +0100
  [PATCH 4.9 02/51] netvsc: add rcu_read locking to netvsc callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 20:00 +0100
  [PATCH 4.9 17/51] virtio-net: restore VIRTIO_HDR_F_DATA_VALID on receiving Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 20:00 +0100
  [PATCH 4.9 07/51] net: ipv4: fix table id in getroute response Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 20:00 +0100
  [PATCH 4.9 01/51] r8152: fix the sw rx checksum is unavailable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 20:00 +0100
  Re: [PATCH 4.9 00/51] 4.9.8-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-02-02 21:40 +0100
    Re: [PATCH 4.9 00/51] 4.9.8-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-02 22:00 +0100
  Re: [PATCH 4.9 00/51] 4.9.8-stable review Guenter Roeck <linux@roeck-us.net> - 2017-02-03 06:20 +0100
    Re: [PATCH 4.9 00/51] 4.9.8-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-03 08:20 +0100

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