From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Tony Luck <tony.luck@intel.com>, Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,
Parav Pandit <parav@mellanox.com>,
Ira Weiny <ira.weiny@intel.com>,
linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] IB/core: Add mitigation for Spectre V1
Date: Tue, 30 Jul 2019 18:52:12 -0500 [thread overview]
Message-ID: <95f5cf70-1a1d-f48c-efac-f389360f585e@embeddedor.com> (raw)
In-Reply-To: <20190730202407.31046-1-tony.luck@intel.com>
On 7/30/19 3:24 PM, Tony Luck wrote:
> Some processors may mispredict an array bounds check and
> speculatively access memory that they should not. With
> a user supplied array index we like to play things safe
> by masking the value with the array size before it is
> used as an index.
>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>
> [I don't have h/w, so just compile tested]
>
> drivers/infiniband/core/user_mad.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
> index 9f8a48016b41..fdce254e4f65 100644
> --- a/drivers/infiniband/core/user_mad.c
> +++ b/drivers/infiniband/core/user_mad.c
> @@ -49,6 +49,7 @@
> #include <linux/sched.h>
> #include <linux/semaphore.h>
> #include <linux/slab.h>
> +#include <linux/nospec.h>
>
> #include <linux/uaccess.h>
>
> @@ -888,6 +889,7 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg)
> mutex_lock(&file->port->file_mutex);
> mutex_lock(&file->mutex);
>
> + id = array_index_nospec(id, IB_UMAD_MAX_AGENTS);
This is wrong. This prevents the below condition id >= IB_UMAD_MAX_AGENTS
from ever being true. And I don't think this is what you want.
> if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) {
> ret = -EINVAL;
> goto out;
>
--
Gustavo
next prev parent reply other threads:[~2019-07-30 23:52 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 20:24 [PATCH] IB/core: Add mitigation for Spectre V1 Tony Luck
2019-07-30 23:34 ` Ira Weiny
2019-07-30 23:52 ` Gustavo A. R. Silva [this message]
2019-07-31 4:28 ` Ira Weiny
2019-07-31 4:39 ` [PATCH V2] " Luck, Tony
2019-07-31 14:52 ` Doug Ledford
2019-07-31 17:52 ` Gustavo A. R. Silva
2019-07-31 18:52 ` Doug Ledford
2019-07-31 19:22 ` Doug Ledford
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