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From: Fenghua Yu <fenghua.yu@intel.com>
To: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>, Ashok Raj <ashok.raj@intel.com>,
	Ravi V Shankar <ravi.v.shankar@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	robin.murphy@arm.com, 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>,
	will@kernel.org
Subject: Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit
Date: Wed, 27 Apr 2022 17:54:57 -0700	[thread overview]
Message-ID: <Ymnl4S6ukb8kgwaq@fyu1.sc.intel.com> (raw)
In-Reply-To: <51514a02-0de9-2f9e-ec0e-c86e147fa74c@linaro.org>

Hi, Dave and Jean,

On Tue, Apr 26, 2022 at 01:04:45PM +0800, Zhangfei Gao wrote:
> 
> 
> On 2022/4/26 下午12:20, Fenghua Yu wrote:
> > Hi, Jean and Zhangfei,
> > 
> > On Mon, Apr 25, 2022 at 05:13:02PM +0100, Jean-Philippe Brucker wrote:
> > > Could we move mm_pasid_drop() to __mmdrop() instead of __mmput()?  For Arm
> > > we do need to hold the mm_count until unbind(), and mmgrab()/mmdrop() is
> > > also part of Lu's rework [1].
> > Is this a right fix for the issue? Could you please test it on ARM?
> > I don't have an ARM machine.
> > 
> > Thanks.
> > 
> > -Fenghua
> > 
> >  From 84aa68f6174439d863c40cdc2db0e1b89d620dd0 Mon Sep 17 00:00:00 2001
> > From: Fenghua Yu <fenghua.yu@intel.com>
> > Date: Fri, 15 Apr 2022 00:51:33 -0700
> > Subject: [PATCH] iommu/sva: Fix PASID use-after-free issue
> > 
> > A PASID might be still used on ARM after it is freed in __mmput().
> > 
> > process:
> > 	open()->sva_bind()->ioasid_alloc() = N; // Get PASID N for the mm
> > 	exit();
> > 	exit_mm()->__mmput()->mm_pasid_drop()->mm->pasid = -1; // PASID -1
> > 	exit_files()->release(dev)->sva_unbind()->use mm->pasid; // Failure
> > 
> > To avoid the use-after-free issue, free the PASID after no device uses it,
> > i.e. after all devices are unbound from the mm.
> > 
> > sva_bind()/sva_unbind() call mmgrab()/mmdrop() to track mm->mm_count.
> > __mmdrop() is called only after mm->mm_count is zero. So freeing the PASID
> > in __mmdrop() guarantees the PASID is safely freed only after no device
> > is bound to the mm.
> > 
> > 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: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Suggested-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> Thanks for the fix.
> 
> Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> 
> 
> > ---
> >   kernel/fork.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/kernel/fork.c b/kernel/fork.c
> > index 9796897560ab..35a3beff140b 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -792,6 +792,7 @@ void __mmdrop(struct mm_struct *mm)
> >   	mmu_notifier_subscriptions_destroy(mm);
> >   	check_mm(mm);
> >   	put_user_ns(mm->user_ns);
> > +	mm_pasid_drop(mm);
> >   	free_mm(mm);
> >   }
> >   EXPORT_SYMBOL_GPL(__mmdrop);
> > @@ -1190,7 +1191,6 @@ static inline void __mmput(struct mm_struct *mm)
> >   	}
> >   	if (mm->binfmt)
> >   		module_put(mm->binfmt->module);
> > -	mm_pasid_drop(mm);
> >   	mmdrop(mm);
> >   }
> 

Is this patch a good fix? Will you help push the fix into upstream?

Thank you very much!

-Fenghua

  reply	other threads:[~2022-04-28  0:54 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
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 [this message]
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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