From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754764AbbIBPLE (ORCPT ); Wed, 2 Sep 2015 11:11:04 -0400 Received: from relay1.sgi.com ([192.48.180.66]:47111 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750743AbbIBPLC (ORCPT ); Wed, 2 Sep 2015 11:11:02 -0400 X-Greylist: delayed 470 seconds by postgrey-1.27 at vger.kernel.org; Wed, 02 Sep 2015 11:11:02 EDT Date: Wed, 2 Sep 2015 10:03:04 -0500 From: Dimitri Sivanich To: Sudip Mukherjee Cc: Arnd Bergmann , Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] drivers/misc/sgi-gru: fix dereference of ERR_PTR Message-ID: <20150902150304.GD26958@sgi.com> References: <1441193098-13885-1-git-send-email-sudipm.mukherjee@gmail.com> <1441193098-13885-4-git-send-email-sudipm.mukherjee@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1441193098-13885-4-git-send-email-sudipm.mukherjee@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 02, 2015 at 04:54:58PM +0530, Sudip Mukherjee wrote: > gru_alloc_gts() can fail and it can return ERR_PTR(errvalue). We should > not dereference it if it has returned error. And incase it has returned > error then just downgrade the write lock and exit. > Not sure about this, because gru_load_kernel_context is expected to complete with a loaded context. Since most if not all error possibilities are out of memory conditions, it might be better to loop (with an msleep(1)) and wait for forward progress, similar to the while loop in this function. > Signed-off-by: Sudip Mukherjee > --- > drivers/misc/sgi-gru/grukservices.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c > index a6fd773..369f7fe 100644 > --- a/drivers/misc/sgi-gru/grukservices.c > +++ b/drivers/misc/sgi-gru/grukservices.c > @@ -161,6 +161,8 @@ static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id) > > if (!bs->bs_kgts) { > bs->bs_kgts = gru_alloc_gts(NULL, 0, 0, 0, 0, 0); > + if (IS_ERR(bs->bs_kgts)) > + goto err_gru_alloc_gts; > bs->bs_kgts->ts_user_blade_id = blade_id; > } > kgts = bs->bs_kgts; > @@ -184,6 +186,7 @@ static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id) > bs->kernel_cb = get_gseg_base_address_cb(vaddr, ctxnum, 0); > bs->kernel_dsr = get_gseg_base_address_ds(vaddr, ctxnum, 0); > } > +err_gru_alloc_gts: > downgrade_write(&bs->bs_kgts_sema); > } > > -- > 1.9.1