From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCA12C54EE9 for ; Fri, 16 Sep 2022 08:16:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229824AbiIPIQF (ORCPT ); Fri, 16 Sep 2022 04:16:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230333AbiIPIPg (ORCPT ); Fri, 16 Sep 2022 04:15:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D35B64D26D for ; Fri, 16 Sep 2022 01:15:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1635B628FF for ; Fri, 16 Sep 2022 08:15:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAB3FC433D7; Fri, 16 Sep 2022 08:15:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663316122; bh=Vmu2pXGR2qKDM5NtYPIEZZuJIRXmOGJUGhaCm1owV00=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KdrtgOKMaJSzn31boNkRiZJUxizzFmsYR6hhr2yc//e8vd4hkK6fCY98EY8wdDaua TuLv3B96CFGoXkZs7e9wM3+7n/Ah2lLlEzNpr/C3nnWJbCkEdo52UVJt51bJs5IJJR HQHKfQbDxfZB6H4+5MegHXK8tTL9ZpUVrMaSimXk= Date: Fri, 16 Sep 2022 10:15:47 +0200 From: Greg KH To: xmzyshypnc <1002992920@qq.com> Cc: dimitri.sivanich@hpe.com, arnd@arndb.de, linux-kernel@vger.kernel.org, hackerzheng666@gmail.com, alex000young@gmail.com, security@kernel.org Subject: Re: [PATCH] misc: sgi-gru: fix use-after-free error in gru_set_context_option, gru_fault and gru_handle_user_call_os Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 16, 2022 at 03:39:57PM +0800, xmzyshypnc wrote: > in drivers/misc/sgi-gru/grufile.c, gru_file_unlocked_ioctl function can be called by user. If the req is GRU_SET_CONTEXT_OPTION, it will call gru_set_context_option. Please properly wrap your changelog text at 72 columns like your editor asked you to when you wrote the changelog text. > > In gru_set_context_option, as req can be controlled by user (copy_from_user(&req, (void __user *)arg, sizeof(req))), we can get into sco_blade_chiplet case and reach gru_check_context_placement function call. > > in gru_check_context_placement function, if the error path was steped, say gru_check_chiplet_assignment return 0, then it will fall into gru_unload_context function,which will call gru_free_gru_context->gts_drop. As gts->ts_refcnt was set to 1 in gru_alloc_gts. It will finnaly call kfree(gts) in gts_drop function. > > Then gru_unlock_gts will be called in gru_set_context_option function. which is a typical Use after free. > > The same problem exists in gru_handle_user_call_os function and gru_fault function. > > Fix it by introduce the return value to see if gts is in good case or not. Free the gts in caller when gru_check_chiplet_assignment check failed. > > Signed-off-by: xmzyshypnc <1002992920@qq.com> > --- > drivers/misc/sgi-gru/grufault.c | 14 ++++++++++++-- > drivers/misc/sgi-gru/grumain.c | 19 +++++++++++++++---- > drivers/misc/sgi-gru/grutables.h | 2 +- > 3 files changed, 28 insertions(+), 7 deletions(-) > > diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c > index d7ef61e602ed..08e837a45ad7 100644 > --- a/drivers/misc/sgi-gru/grufault.c > +++ b/drivers/misc/sgi-gru/grufault.c > @@ -656,7 +656,13 @@ int gru_handle_user_call_os(unsigned long cb) > if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE) > goto exit; > > - gru_check_context_placement(gts); > + ret = gru_check_context_placement(gts); > + > + if (ret) { No blank line needed. > + gru_unlock_gts(gts); > + gru_unload_context(gts, 1); > + return -EINVAL; Jump to an error block at the end of the function instead? > + } > > /* > * CCH may contain stale data if ts_force_cch_reload is set. > @@ -874,7 +880,7 @@ int gru_set_context_option(unsigned long arg) > } else { > gts->ts_user_blade_id = req.val1; > gts->ts_user_chiplet_id = req.val0; > - gru_check_context_placement(gts); > + ret = gru_check_context_placement(gts); > } > break; > case sco_gseg_owner: > @@ -889,6 +895,10 @@ int gru_set_context_option(unsigned long arg) > ret = -EINVAL; > } > gru_unlock_gts(gts); > + if (ret) { > + gru_unload_context(gts, 1); > + ret = -EINVAL; > + } > > return ret; > } > diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c > index 9afda47efbf2..e1ecf86df3c1 100644 > --- a/drivers/misc/sgi-gru/grumain.c > +++ b/drivers/misc/sgi-gru/grumain.c > @@ -716,9 +716,10 @@ static int gru_check_chiplet_assignment(struct gru_state *gru, > * chiplet. Misassignment can occur if the process migrates to a different > * blade or if the user changes the selected blade/chiplet. > */ > -void gru_check_context_placement(struct gru_thread_state *gts) > +int gru_check_context_placement(struct gru_thread_state *gts) > { > struct gru_state *gru; > + int ret = 0; > > /* > * If the current task is the context owner, verify that the > @@ -727,14 +728,16 @@ void gru_check_context_placement(struct gru_thread_state *gts) > */ > gru = gts->ts_gru; > if (!gru || gts->ts_tgid_owner != current->tgid) > - return; > + return ret; Why is this succeeding if there was an error? > > if (!gru_check_chiplet_assignment(gru, gts)) { > STAT(check_context_unload); > - gru_unload_context(gts, 1); > + ret = 1; 1 is not a valid error value; > } else if (gru_retarget_intr(gts)) { > STAT(check_context_retarget_intr); > } > + > + return ret; > } > > > @@ -919,6 +922,7 @@ vm_fault_t gru_fault(struct vm_fault *vmf) > struct gru_thread_state *gts; > unsigned long paddr, vaddr; > unsigned long expires; > + int ret; > > vaddr = vmf->address; > gru_dbg(grudev, "vma %p, vaddr 0x%lx (0x%lx)\n", > @@ -934,7 +938,12 @@ vm_fault_t gru_fault(struct vm_fault *vmf) > mutex_lock(>s->ts_ctxlock); > preempt_disable(); > > - gru_check_context_placement(gts); > + ret = gru_check_context_placement(gts); > + if (ret) { > + mutex_unlock(>s->ts_ctxlock); > + gru_unload_context(gts, 1); > + return VM_FAULT_NOPAGE; Why not return ret? > + } > > if (!gts->ts_gru) { > STAT(load_user_context); > @@ -958,6 +967,8 @@ vm_fault_t gru_fault(struct vm_fault *vmf) > preempt_enable(); > mutex_unlock(>s->ts_ctxlock); > > + > + Why the blank lines added? thanks, greg k-h