From: Al Viro viro@zeniv.linux.org.uk
mainline inclusion from mainline-v5.14-rc1 commit c0c3b8d380a8f54c75786d41f6f9efbe761dac6c category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4OM1C CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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We can do that more or less safely, since the parent is held locked all along. Yes, somebody might observe the object via dcache, only to have it disappear afterwards, but there's really no good way to prevent that. It won't race with other bind(2) or attempts to move the sucker elsewhere, or put something else in its place - locked parent prevents that.
Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: David S. Miller davem@davemloft.net
Conflicts: net/unix/af_unix.c
Signed-off-by: Baisong Zhong zhongbaisong@huawei.com Reviewed-by: Yue Haibing yuehaibing@huawei.com Reviewed-by: Wei Yongjun weiyongjun1@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- net/unix/af_unix.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index fbb7dcaf7d85..a443b8862c4c 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1051,20 +1051,13 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr) err = security_path_mknod(&parent, dentry, mode, 0); if (!err) err = vfs_mknod(d_inode(parent.dentry), dentry, mode, 0); - if (err) { - done_path_create(&parent, dentry); - return err; - } + if (err) + goto out; err = mutex_lock_interruptible(&u->bindlock); - if (err) { - done_path_create(&parent, dentry); - return err; - } - if (u->addr) { - mutex_unlock(&u->bindlock); - done_path_create(&parent, dentry); - return -EINVAL; - } + if (err) + goto out_unlink; + if (u->addr) + goto out_unlock;
addr->hash = UNIX_HASH_SIZE; hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1); @@ -1076,6 +1069,16 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr) mutex_unlock(&u->bindlock); done_path_create(&parent, dentry); return 0; + +out_unlock: + mutex_unlock(&u->bindlock); + err = -EINVAL; +out_unlink: + /* failed after successful mknod? unlink what we'd created... */ + vfs_unlink(d_inode(parent.dentry), dentry, NULL); +out: + done_path_create(&parent, dentry); + return err; }
static int unix_bind_abstract(struct sock *sk, struct unix_address *addr)