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From: Fenghua Yu <fenghua.yu@intel.com>
To: "zhangfei.gao@foxmail.com" <zhangfei.gao@foxmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Joerg Roedel <joro@8bytes.org>,
	jean-philippe <jean-philippe@linaro.org>,
	Ravi V Shankar <ravi.v.shankar@intel.com>,
	Tony Luck <tony.luck@intel.com>, Ashok Raj <ashok.raj@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>, x86 <x86@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	iommu <iommu@lists.linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
Date: Fri, 15 Apr 2022 03:50:36 -0700	[thread overview]
Message-ID: <YllN/OmjpYdT1tO9@otcwcpicx3.sc.intel.com> (raw)
In-Reply-To: <99bcb9f5-4776-9c40-a776-cdecfa9e1010@foxmail.com>

Hi, Zhangfei,

On Fri, Apr 15, 2022 at 06:14:09PM +0800, zhangfei.gao@foxmail.com wrote:
> 
> 
> On 2022/4/15 下午5:51, Fenghua Yu wrote:
> > On Thu, Apr 14, 2022 at 06:08:09PM +0800, zhangfei.gao@foxmail.com wrote:
> > > On 2022/4/12 下午11:35, zhangfei.gao@foxmail.com wrote:
> > > > Hi, Fenghua
> > > > 
> > > > On 2022/4/12 下午9:41, Fenghua Yu wrote:
> >  From a6444e1e5bd8076f5e5c5e950d3192de327f0c9c Mon Sep 17 00:00:00 2001
> > From: Fenghua Yu <fenghua.yu@intel.com>
> > Date: Fri, 15 Apr 2022 00:51:33 -0700
> > Subject: [RFC PATCH] iommu/sva: Fix PASID use-after-free issue
> > 
> > A PASID might be still used even though it is freed on mm exit.
> > 
> > process A:
> > 	sva_bind();
> > 	ioasid_alloc() = N; // Get PASID N for the mm
> > 	fork(): // spawn process B
> > 	exit();
> > 	ioasid_free(N);
> > 
> > process B:
> > 	device uses PASID N -> failure
> > 	sva_unbind();
> > 
> > Dave Hansen suggests to take a refcount on the mm whenever binding the
> > PASID to a device and drop the refcount on unbinding. The mm won't be
> > dropped if the PASID is still bound to it.
> > 
> > Fixes: 701fac40384f ("iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit")
> > 
> > Reported-by: Zhangfei Gao <zhangfei.gao@foxmail.com>
> > Suggested-by: Dave Hansen" <dave.hansen@linux.intel.com>
> > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> > ---
> >   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 6 ++++++
> >   drivers/iommu/intel/svm.c                       | 4 ++++
> >   2 files changed, 10 insertions(+)
> > 
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > index 22ddd05bbdcd..3fcb842a0df0 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > @@ -7,6 +7,7 @@
> >   #include <linux/mmu_context.h>
> >   #include <linux/mmu_notifier.h>
> >   #include <linux/slab.h>
> > +#include <linux/sched/mm.h>
> >   #include "arm-smmu-v3.h"
> >   #include "../../iommu-sva-lib.h"
> > @@ -363,6 +364,9 @@ arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
> >   	mutex_lock(&sva_lock);
> >   	handle = __arm_smmu_sva_bind(dev, mm);
> > +	/* Take an mm refcount on a successful bind. */
> > +	if (!IS_ERR(handle))
> > +		mmget(mm);
> >   	mutex_unlock(&sva_lock);
> >   	return handle;
> >   }
> > @@ -372,6 +376,8 @@ void arm_smmu_sva_unbind(struct iommu_sva *handle)
> >   	struct arm_smmu_bond *bond = sva_to_bond(handle);
> >   	mutex_lock(&sva_lock);
> > +	/* Drop an mm refcount. */
> > +	mmput(bond->mm);
> >   	if (refcount_dec_and_test(&bond->refs)) {
> >   		list_del(&bond->list);
> >   		arm_smmu_mmu_notifier_put(bond->smmu_mn);
> > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> > index 23a38763c1d1..345a0d5d7922 100644
> > --- a/drivers/iommu/intel/svm.c
> > +++ b/drivers/iommu/intel/svm.c
> > @@ -403,6 +403,8 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
> >   		goto free_sdev;
> >   	list_add_rcu(&sdev->list, &svm->devs);
> > +	/* Take an mm refcount on binding mm. */
> > +	mmget(mm);
> >   success:
> >   	return &sdev->sva;
> > @@ -465,6 +467,8 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid)
> >   				kfree(svm);
> >   			}
> >   		}
> > +		/* Drop an mm reference on unbinding mm. */
> > +		mmput(mm);
> >   	}
> >   out:
> >   	return ret;
> This patch can not be applied on 5.18-rc2 for intel part.

What error do you see? Could you please send to me errors?

I download this patch from:
https://lore.kernel.org/lkml/YllADL6uMoLllzQo@fyu1.sc.intel.com/raw
git am to either v5.18-rc2 or the latest upstream without any issue.

> It should work for arm.
> 
> In fact I have a similar patch at hand but pending since I found an issue.
> 
> I start & stop nginx via this cmd.
> //start
> sudo sbin/nginx                    // this alloc an ioasid=1
> //stop
> sudo sbin/nginx -s quit    // this does not free ioasid=1, but still alloc
> ioasid=2.
> So ioasid will keep allocated but not freed if continue start/stop nginx, 
> though not impact the nginx function.
> 
> stop nginx with -s quit still calls
> src/core/nginx.c
> main -> ngx_ssl_init -> openssl engine:    bind_fn -> ... -> alloc asid
> But openssl engine: ENGINE_free is not called
> 
> Still in checking nginx code.
> 
> Or do you test with nginx?

On my X86 machine, nginx doesn't trigger the kernel sva binding function
to allocate ioasid. I tried pre- nstalled nginx/openssl and also tried my built
a few versions of nginx/openssl. nginx does call OPENSSL_init_ssl() but
doesn't go to the binding function. Don't know if it's my configuration issue.
Maybe you can give me some advice?

I test the patch with a few internal test tools and observe mmget()/mmput()
works fine in various cases.

Thanks.

-Fenghua 

  parent reply	other threads:[~2022-04-15 10:51 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-07 23:02 [PATCH v4 00/11] Re-enable ENQCMD and PASID MSR Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 01/11] iommu/sva: Rename CONFIG_IOMMU_SVA_LIB to CONFIG_IOMMU_SVA Fenghua Yu
2022-02-08  2:39   ` Lu Baolu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 02/11] mm: Change CONFIG option for mm->pasid field Fenghua Yu
2022-02-08  2:40   ` Lu Baolu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 03/11] iommu/ioasid: Introduce a helper to check for valid PASIDs Fenghua Yu
2022-02-08  2:40   ` Lu Baolu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 04/11] kernel/fork: Initialize mm's PASID Fenghua Yu
2022-02-14 17:23   ` Thomas Gleixner
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit Fenghua Yu
2022-02-08  2:41   ` Lu Baolu
2022-02-08 15:01     ` Fenghua Yu
2022-02-10  3:16   ` Jacob Pan
2022-02-10 16:27     ` Fenghua Yu
2022-02-10 17:24       ` Luck, Tony
2022-02-10 18:31         ` Fenghua Yu
2022-02-10 23:52           ` Fenghua Yu
2022-02-10 18:49     ` Jacob Pan
2022-02-10 23:15       ` Fenghua Yu
2022-02-11 22:00   ` Dave Hansen
2022-02-14 17:24   ` Thomas Gleixner
2022-02-15  9:55   ` Joerg Roedel
     [not found]     ` <tencent_F6830A1196DB4C6A904D7C691F0D961D1108@qq.com>
2022-04-11 14:10       ` Dave Hansen
2022-04-11 14:20         ` zhangfei.gao
2022-04-11 14:36           ` Dave Hansen
2022-04-11 14:44             ` zhangfei.gao
2022-04-11 14:52               ` Dave Hansen
2022-04-11 15:13                 ` zhangfei.gao
2022-04-12  7:04                 ` zhangfei.gao
2022-04-12 13:41                   ` Fenghua Yu
2022-04-12 14:39                     ` Dave Hansen
2022-04-15  9:59                       ` Fenghua Yu
2022-04-12 15:35                     ` zhangfei.gao
2022-04-14 10:08                       ` zhangfei.gao
2022-04-15  9:51                         ` Fenghua Yu
     [not found]                           ` <99bcb9f5-4776-9c40-a776-cdecfa9e1010@foxmail.com>
2022-04-15 10:14                             ` zhangfei.gao
2022-04-15 10:50                             ` Fenghua Yu [this message]
2022-04-15 11:52                               ` zhangfei.gao
2022-04-15 12:37                                 ` Fenghua Yu
2022-04-16  1:30                                   ` zhangfei.gao
2022-04-15 19:07                                 ` Fenghua Yu
2022-04-15 21:00                                 ` Jacob Pan
2022-04-16  1:43                                   ` zhangfei.gao
2022-04-18 18:14                                     ` Jacob Pan
2022-04-19  1:02                                       ` zhangfei.gao
2022-04-18  6:34                                   ` Tian, Kevin
2022-04-18 18:11                                     ` Jacob Pan
2022-04-20 16:45                           ` Jean-Philippe Brucker
2022-04-21  6:47                             ` zhangfei.gao
2022-04-22  9:03                               ` zhangfei.gao
2022-04-22 10:11                                 ` Jean-Philippe Brucker
2022-04-22 13:15                                   ` zhangfei.gao
2022-04-22 15:50                                     ` Jean-Philippe Brucker
2022-04-23 11:13                                       ` zhangfei.gao
2022-04-24  2:58                                         ` Zhangfei Gao
2022-04-24  9:52                                           ` Zhangfei Gao
2022-04-25 13:53                                         ` Jean-Philippe Brucker
2022-04-25 14:18                                           ` Dave Hansen
2022-04-25 14:26                                             ` Jean-Philippe Brucker
2022-04-25 15:34                                               ` Jacob Pan
2022-04-25 16:13                                                 ` Jean-Philippe Brucker
2022-04-25 22:32                                                   ` Jacob Pan
2022-04-26  4:20                                                   ` Fenghua Yu
2022-04-26  5:04                                                     ` Zhangfei Gao
2022-04-28  0:54                                                       ` Fenghua Yu
2022-04-28  8:43                                                         ` Jean-Philippe Brucker
2022-04-28 15:09                                                     ` Dave Hansen
2022-04-28 15:28                                                       ` Fenghua Yu
2022-04-28 15:42                                                         ` Dave Hansen
2022-04-28 16:01                                                       ` Jean-Philippe Brucker
2022-04-28 16:35                                                         ` Dave Hansen
2022-04-26  4:28                                                   ` Zhangfei Gao
2022-04-26  4:36                                                     ` Fenghua Yu
2022-04-26  5:19                                                       ` Zhangfei Gao
2022-04-25 15:55                                               ` Dave Hansen
2022-04-25 16:40                                                 ` Jean-Philippe Brucker
2022-04-26 15:27                                                   ` Dave Hansen
2022-04-26 16:48                                                     ` Jean-Philippe Brucker
2022-04-26 23:31                                                       ` Dave Hansen
2022-04-28  8:39                                                         ` Jean-Philippe Brucker
2022-04-29  7:53                                                           ` Baolu Lu
2022-04-29 13:51                                                             ` Fenghua Yu
2022-04-29 14:34                                                               ` Jean-Philippe Brucker
2022-04-29 22:19                                                                 ` Fenghua Yu
2022-04-30  7:33                                                                   ` Baolu Lu
2022-05-03  7:49                                                                     ` Jean-Philippe Brucker
2022-05-06  5:36                                                                       ` Baolu Lu
2022-04-12 14:36                   ` Dave Hansen
2022-04-12 15:10                     ` Jean-Philippe Brucker
2022-04-12 15:35                       ` Dave Hansen
2022-04-13 11:14                         ` Lu Baolu
2022-04-25  2:57                         ` zhangfei.gao
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 06/11] x86/fpu: Clear PASID when copying fpstate Fenghua Yu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 07/11] sched: Define and initialize a flag to identify valid PASID in the task Fenghua Yu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Peter Zijlstra
2022-02-07 23:02 ` [PATCH v4 08/11] x86/traps: Demand-populate PASID MSR via #GP Fenghua Yu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 09/11] x86/cpufeatures: Re-enable ENQCMD Fenghua Yu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 10/11] tools/objtool: Check for use of the ENQCMD instruction in the kernel Fenghua Yu
2022-02-15 10:54   ` [tip: x86/pasid] " tip-bot2 for Fenghua Yu
2022-03-09  7:55   ` [tip: x86/core] " tip-bot2 for Fenghua Yu
2022-03-15 10:44   ` tip-bot2 for Fenghua Yu
2022-02-07 23:02 ` [PATCH v4 11/11] docs: x86: Change documentation for SVA (Shared Virtual Addressing) Fenghua Yu
2022-02-14 17:25   ` Thomas Gleixner
2022-02-15 10:54   ` [tip: x86/pasid] Documentation/x86: Update " tip-bot2 for Fenghua Yu
2022-02-11 20:04 ` [PATCH v4 00/11] Re-enable ENQCMD and PASID MSR Fenghua Yu

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