Re: [PATCH 14/18] ipv4: prevent bounds-check bypass via speculative execution

Sergei Shtylyov
2018-01-06T10:04:52Z

On 1/6/2018 4:11 AM, Dan Williams wrote:

> Static analysis reports that 'offset' may be a user controlled value
> that is used as a data dependency reading from a raw_frag_vec buffer.
> In order to avoid potential leaks of kernel memory values, block
> speculative execution of the instruction stream that could issue further
> reads based on an invalid '*(rfv->c + offset)' value.
>
> Based on an original patch by Elena Reshetova.
>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> net/ipv4/raw.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 125c1eab3eaa..f72b20131a15 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
[...]
> @@ -472,17 +473,17 @@ static int raw_getfrag(void *from, char *to, int offset, int len, int odd,
> struct sk_buff *skb)
> {
> struct raw_frag_vec *rfv = from;
> + char *rfv_buf;
>
> - if (offset < rfv->hlen) {
> + if ((rfv_buf = nospec_array_ptr(rfv->hdr.c, offset, rfv->hlen))) {

And here...

[...]

MBR, Sergei