From: Rohith Surabattula <rohiths@microsoft.com>
Date: Thu, 29 Jul 2021 07:45:29 +0000 (+0000)
Subject: cifs: Handle race conditions during rename
X-Git-Tag: v5.13.12~139
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=3c420ec439715616dfe189d38169f71df612a086;p=wrapfs-5.3.y.git

cifs: Handle race conditions during rename

commit 41535701da3324b80029cabb501e86c4fafe339d upstream.

When rename is executed on directory which has files for which
close is deferred, then rename will fail with EACCES.

This patch will try to close all deferred files when EACCES is received
and retry rename on a directory.

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Cc: stable@vger.kernel.org # 5.13
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index f60f068d33e8..5b8789b24531 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -1637,7 +1637,7 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
 		goto unlink_out;
 	}
 
-	cifs_close_all_deferred_files(tcon);
+	cifs_close_deferred_file(CIFS_I(inode));
 	if (cap_unix(tcon->ses) && (CIFS_UNIX_POSIX_PATH_OPS_CAP &
 				le64_to_cpu(tcon->fsUnixInfo.Capability))) {
 		rc = CIFSPOSIXDelFile(xid, tcon, full_path,
@@ -2096,6 +2096,7 @@ cifs_rename2(struct user_namespace *mnt_userns, struct inode *source_dir,
 	FILE_UNIX_BASIC_INFO *info_buf_target;
 	unsigned int xid;
 	int rc, tmprc;
+	int retry_count = 0;
 
 	if (flags & ~RENAME_NOREPLACE)
 		return -EINVAL;
@@ -2125,10 +2126,24 @@ cifs_rename2(struct user_namespace *mnt_userns, struct inode *source_dir,
 		goto cifs_rename_exit;
 	}
 
-	cifs_close_all_deferred_files(tcon);
+	cifs_close_deferred_file(CIFS_I(d_inode(source_dentry)));
+	if (d_inode(target_dentry) != NULL)
+		cifs_close_deferred_file(CIFS_I(d_inode(target_dentry)));
+
 	rc = cifs_do_rename(xid, source_dentry, from_name, target_dentry,
 			    to_name);
 
+	if (rc == -EACCES) {
+		while (retry_count < 3) {
+			cifs_close_all_deferred_files(tcon);
+			rc = cifs_do_rename(xid, source_dentry, from_name, target_dentry,
+					    to_name);
+			if (rc != -EACCES)
+				break;
+			retry_count++;
+		}
+	}
+
 	/*
 	 * No-replace is the natural behavior for CIFS, so skip unlink hacks.
 	 */
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index cccaccfb02d0..90f380a1b618 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -735,13 +735,19 @@ void
 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 {
 	struct cifsFileInfo *cfile = NULL;
-	struct cifs_deferred_close *dclose;
+
+	if (cifs_inode == NULL)
+		return;
 
 	list_for_each_entry(cfile, &cifs_inode->openFileList, flist) {
-		spin_lock(&cifs_inode->deferred_lock);
-		if (cifs_is_deferred_close(cfile, &dclose))
-			mod_delayed_work(deferredclose_wq, &cfile->deferred, 0);
-		spin_unlock(&cifs_inode->deferred_lock);
+		if (delayed_work_pending(&cfile->deferred)) {
+			/*
+			 * If there is no pending work, mod_delayed_work queues new work.
+			 * So, Increase the ref count to avoid use-after-free.
+			 */
+			if (!mod_delayed_work(deferredclose_wq, &cfile->deferred, 0))
+				cifsFileInfo_get(cfile);
+		}
 	}
 }