linux-kernel - Re: [PATCH 1/1] cifs: potential memory leaks when parsing mnt opts

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Date:	Mon, 23 Mar 2015 23:43:55 -0500
From:	Steve French <smfrench@...il.com>
To:	Taesoo Kim <tsgatesv@...il.com>
Cc:	Steve French <sfrench@...ba.org>,
	"linux-cifs@...r.kernel.org" <linux-cifs@...r.kernel.org>,
	samba-technical <samba-technical@...ts.samba.org>,
	LKML <linux-kernel@...r.kernel.org>, taesoo@...ech.edu,
	changwoo@...ech.edu, sanidhya@...ech.edu, blee@...ech.edu,
	csong84@...ech.edu, Scott Lovenberg <scott.lovenberg@...il.com>
Subject: Re: [PATCH 1/1] cifs: potential memory leaks when parsing mnt opts

Nice catch.

Merged into cifs-2.6.git for-next

On Sat, Mar 21, 2015 at 6:08 PM, Taesoo Kim <tsgatesv@...il.com> wrote:
> For example, when mount opt is redundently specified
> (e.g., "user=A,user=B,user=C"), kernel kept allocating new key/val
> with kstrdup() and overwrite previous ptr (to be freed).
>
> Althouhg mkfs.cifs in userspace performs a bit of sanitization
> (e.g., forcing one user option), current implementation is not
> robust. Other options such as iocharset and domainanme are similary
> vulnerable.
>
> Signed-off-by: Taesoo Kim <tsgatesv@...il.com>
> ---
>  fs/cifs/connect.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index d3aa999..4cb8450 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -1599,6 +1599,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>                                 pr_warn("CIFS: username too long\n");
>                                 goto cifs_parse_mount_err;
>                         }
> +
> +                       kfree(vol->username);
>                         vol->username = kstrdup(string, GFP_KERNEL);
>                         if (!vol->username)
>                                 goto cifs_parse_mount_err;
> @@ -1700,6 +1702,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>                                 goto cifs_parse_mount_err;
>                         }
>
> +                       kfree(vol->domainname);
>                         vol->domainname = kstrdup(string, GFP_KERNEL);
>                         if (!vol->domainname) {
>                                 pr_warn("CIFS: no memory for domainname\n");
> @@ -1731,6 +1734,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>                         }
>
>                          if (strncasecmp(string, "default", 7) != 0) {
> +                               kfree(vol->iocharset);
>                                 vol->iocharset = kstrdup(string,
>                                                          GFP_KERNEL);
>                                 if (!vol->iocharset) {
> --
> 2.3.3
>



-- 
Thanks,

Steve
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