| Subject | Re: [PATCH 13/18] ipv6: prevent bounds-check bypass via speculative execution | From | Sergei Shtylyov <> | Date | Sat, 6 Jan 2018 13:04:05 +0300 |
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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
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