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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Aurelien Aptel <aaptel@suse.com>,
        Ronnie Sahlberg <lsahlber@redhat.com>,
        Steve French <stfrench@microsoft.com>
Subject: [PATCH 5.12 039/127] cifs: fix memory leak in smb2_copychunk_range
Date:   Mon, 24 May 2021 17:25:56 +0200
Message-Id: <20210524152336.172737530@linuxfoundation.org>
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From: Ronnie Sahlberg <lsahlber@redhat.com>

commit d201d7631ca170b038e7f8921120d05eec70d7c5 upstream.

When using smb2_copychunk_range() for large ranges we will
run through several iterations of a loop calling SMB2_ioctl()
but never actually free the returned buffer except for the final
iteration.
This leads to memory leaks everytime a large copychunk is requested.

Fixes: 9bf0c9cd4314 ("CIFS: Fix SMB2/SMB3 Copy offload support (refcopy) for large files")
Cc: <stable@vger.kernel.org>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/cifs/smb2ops.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1822,6 +1822,8 @@ smb2_copychunk_range(const unsigned int
 			cpu_to_le32(min_t(u32, len, tcon->max_bytes_chunk));
 
 		/* Request server copy to target from src identified by key */
+		kfree(retbuf);
+		retbuf = NULL;
 		rc = SMB2_ioctl(xid, tcon, trgtfile->fid.persistent_fid,
 			trgtfile->fid.volatile_fid, FSCTL_SRV_COPYCHUNK_WRITE,
 			true /* is_fsctl */, (char *)pcchunk,