linux-kernel - Q: cifs, freeing volume

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Date:	Tue, 16 Aug 2011 08:22:17 +0900
From:	"J. R. Okajima" <hooanon05@...oo.co.jp>
To:	smfrench@...il.com, linux-cifs@...r.kernel.org
cc:	linux-kernel@...r.kernel.org, kirk w <kirkpuppy@...oo.com>
Subject: Q: cifs, freeing volume_info->UNCip

Hello,

CIFS cleanup_volume_info_contents() looks like having a memory
corruption problem.
When UNCip is set to "&vol->UNC[2]" in cifs_parse_mount_options(), it
should not be kfree()-ed in cleanup_volume_info_contents().

If it is correct and the code in mainline is not fixed yet, then here is
a patch.

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index ccc1afa..e0ea721 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2838,7 +2838,8 @@ cleanup_volume_info_contents(struct smb_vol *volume_info)
 	kfree(volume_info->username);
 	kzfree(volume_info->password);
 	kfree(volume_info->UNC);
-	kfree(volume_info->UNCip);
+	if (volume_info->UNCip != volume_info->UNC + 2)
+		kfree(volume_info->UNCip);
 	kfree(volume_info->domainname);
 	kfree(volume_info->iocharset);
 	kfree(volume_info->prepath);

J. R. Okajima
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