lkml.org 
[lkml]   [2018]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 13/18] ipv6: prevent bounds-check bypass via speculative execution
From
Date
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 raw6_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/ipv6/raw.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
> index 761a473a07c5..384e3d59d148 100644
> --- a/net/ipv6/raw.c
> +++ b/net/ipv6/raw.c
[...]
> @@ -725,17 +726,17 @@ static int raw6_getfrag(void *from, char *to, int offset, int len, int odd,
> struct sk_buff *skb)
> {
> struct raw6_frag_vec *rfv = from;
> + char *rfv_buf;
>
> - if (offset < rfv->hlen) {
> + if ((rfv_buf = nospec_array_ptr(rfv->c, offset, rfv->hlen))) {

And here...

> int copy = min(rfv->hlen - offset, len);
>
> if (skb->ip_summed == CHECKSUM_PARTIAL)
> - memcpy(to, rfv->c + offset, copy);
> + memcpy(to, rfv_buf, copy);
> else
> skb->csum = csum_block_add(
> skb->csum,
> - csum_partial_copy_nocheck(rfv->c + offset,
> - to, copy, 0),
> + csum_partial_copy_nocheck(rfv_buf, to, copy, 0),
> odd);
>
> odd = 0;

MBR, Sergei

\
 
 \ /
  Last update: 2018-01-06 11:05    [W:0.475 / U:0.316 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site