[patch] cifs: integer overflow in parse_dacl()

[Shirish Pargaonkar]

On Wed, Jan 11, 2012 at 1:46 AM, Dan Carpenter <dan.carpenter at oracle.com> wrote:
> On 32 bit systems num_aces * sizeof(struct cifs_ace *) could overflow
> leading to a smaller ppace buffer than we expected.
>
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
>
> diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
> index 72ddf23..c1b2544 100644
> --- a/fs/cifs/cifsacl.c
> +++ b/fs/cifs/cifsacl.c
> @@ -909,6 +909,8 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
>                umode_t group_mask = S_IRWXG;
>                umode_t other_mask = S_IRWXU | S_IRWXG | S_IRWXO;
>
> +               if (num_aces > ULONG_MAX / sizeof(struct cifs_ace *))

Should an error/warning (like cifs client can't handle these many aces or
possible erroneous number of aces sent by server etc.) be logged before
returning?

> +                       return;
>                ppace = kmalloc(num_aces * sizeof(struct cifs_ace *),
>                                GFP_KERNEL);
>                if (!ppace) {
> --
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