linux-kernel - [PATCH 5.15 028/667] cifs: fix potential double free during failed mount

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Message-Id: <20220607164935.640274400@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 18:54:53 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Roberto Bergantinos <rbergant@...hat.com>,
        Ronnie Sahlberg <lsahlber@...hat.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 5.15 028/667] cifs: fix potential double free during failed mount

From: Ronnie Sahlberg <lsahlber@...hat.com>

commit 8378a51e3f8140f60901fb27208cc7a6e47047b5 upstream.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=2088799

Cc: stable@...r.kernel.org
Signed-off-by: Roberto Bergantinos <rbergant@...hat.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@...hat.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/cifs/cifsfs.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -826,7 +826,7 @@ cifs_smb3_do_mount(struct file_system_ty
 	      int flags, struct smb3_fs_context *old_ctx)
 {
 	int rc;
-	struct super_block *sb;
+	struct super_block *sb = NULL;
 	struct cifs_sb_info *cifs_sb = NULL;
 	struct cifs_mnt_data mnt_data;
 	struct dentry *root;
@@ -922,9 +922,11 @@ out_super:
 	return root;
 out:
 	if (cifs_sb) {
-		kfree(cifs_sb->prepath);
-		smb3_cleanup_fs_context(cifs_sb->ctx);
-		kfree(cifs_sb);
+		if (!sb || IS_ERR(sb)) {  /* otherwise kill_sb will handle */
+			kfree(cifs_sb->prepath);
+			smb3_cleanup_fs_context(cifs_sb->ctx);
+			kfree(cifs_sb);
+		}
 	}
 	return root;
 }