Messages in this thread | | | Subject | Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit | From | "" <> | Date | Fri, 15 Apr 2022 19:52:03 +0800 |
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On 2022/4/15 下午6:50, Fenghua Yu wrote: > 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 is my copy paste issue.
I have tested, nginx woks well.
Other than the following issue, Each time /sbin/nginx will alloc ioasid but not free. which I think it maybe nginx issue or the mis-usage, will ask there.
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> >> 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 am using openssl engine, which use crypto driver and using sva via uacce. nginx -> openssl -> openssl engine -> sva related.
> > I test the patch with a few internal test tools and observe mmget()/mmput() > works fine in various cases. OK, thanks
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