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authorWANG Cong <xiyou.wangcong@gmail.com>2017-01-23 22:17:35 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-04 11:45:09 +0300
commit0492a033fb71b5ef0573aa157aadda049e8a7770 (patch)
treee3ed6418ab81fa0ed94a02ee7eeab1f3ba3c536e
parente674c70bafe78f96ca63b645b7881744c82b5586 (diff)
downloadlinux-0492a033fb71b5ef0573aa157aadda049e8a7770.tar.xz
af_unix: move unix_mknod() out of bindlock
[ 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>
-rw-r--r--net/unix/af_unix.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 73f75258ce46..b2e934ff2448 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -994,6 +994,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
unsigned int hash;
struct unix_address *addr;
struct hlist_head *list;
+ struct path path = { NULL, NULL };
err = -EINVAL;
if (sunaddr->sun_family != AF_UNIX)
@@ -1009,9 +1010,20 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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)
@@ -1028,16 +1040,6 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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);
@@ -1064,6 +1066,9 @@ out_unlock:
spin_unlock(&unix_table_lock);
out_up:
mutex_unlock(&u->bindlock);
+out_put:
+ if (err)
+ path_put(&path);
out:
return err;
}