From: Jason Gunthorpe <jgg@ziepe.ca>
To: Divya Indi <divya.indi@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
"Kaike Wan" <kaike.wan@intel.com>,
"Gerd Rausch" <gerd.rausch@oracle.com>,
"Håkon Bugge" <haakon.bugge@oracle.com>,
"Srinivas Eeda" <srinivas.eeda@oracle.com>,
"Rama Nichanamatlu" <rama.nichanamatlu@oracle.com>,
"Doug Ledford" <dledford@redhat.com>
Subject: Re: [PATCH] IB/sa: Resolving use-after-free in ib_nl_send_msg.
Date: Mon, 25 May 2020 21:31:10 -0300 [thread overview]
Message-ID: <20200526003110.GJ744@ziepe.ca> (raw)
In-Reply-To: <1589469084-15125-2-git-send-email-divya.indi@oracle.com>
On Thu, May 14, 2020 at 08:11:24AM -0700, Divya Indi wrote:
> static void ib_nl_set_path_rec_attrs(struct sk_buff *skb,
> struct ib_sa_query *query)
> {
> @@ -889,6 +904,15 @@ static int ib_nl_make_request(struct ib_sa_query *query, gfp_t gfp_mask)
> spin_lock_irqsave(&ib_nl_request_lock, flags);
> list_del(&query->list);
> spin_unlock_irqrestore(&ib_nl_request_lock, flags);
> + } else {
> + set_bit(IB_SA_NL_QUERY_SENT, (unsigned long *)&query->flags);
> +
> + /*
> + * If response is received before this flag was set
> + * someone is waiting to process the response and release the
> + * query.
> + */
> + wake_up(&wait_queue);
> }
As far as I can see the issue here is that the request is put into the
ib_nl_request_list before it is really ready to be in that list, eg
ib_nl_send_msg() has actually completed and ownership of the memory
has been transfered.
It appears to me the reason for this is simply because a spinlock is
used for the ib_nl_request_lock and it cannot be held across
ib_nl_send_msg().
Convert that lock to a mutex and move the list_add to after the
success of ib_nl_send_msg() and this bug should be fixed without
adding jaunty atomics or a wait queue.
This is a 'racy error unwind' bug class...
Jason
prev parent reply other threads:[~2020-05-26 0:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-14 15:11 Review Request Divya Indi
2020-05-14 15:11 ` [PATCH] IB/sa: Resolving use-after-free in ib_nl_send_msg Divya Indi
2020-05-26 0:31 ` Jason Gunthorpe [this message]
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