From c0c3b8d380a8f54c75786d41f6f9efbe761dac6c Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 19 Jun 2021 03:50:32 +0000
Subject: unix_bind_bsd(): unlink if we fail after successful mknod
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>
---
net/unix/af_unix.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
(limited to 'net/unix/af_unix.c')
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 25dda9ca9d15..42a9e0730344 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1010,20 +1010,13 @@ 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(ns, 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);
@@ -1035,6 +1028,16 @@ 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(ns, d_inode(parent.dentry), dentry, NULL);
+out:
+ done_path_create(&parent, dentry);
+ return err;
}
static int unix_bind_abstract(struct sock *sk, unsigned hash,
--
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