From: Zhangfei Gao <zhangfei.gao@linaro.org>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>,
will@kernel.org, robin.murphy@arm.com, joro@8bytes.org
Cc: iommu@lists.linux-foundation.org
Subject: Re: [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free
Date: Tue, 26 Apr 2022 21:52:50 +0800 [thread overview]
Message-ID: <198ae560-dbea-2c92-ec27-ca26b36b250e@linaro.org> (raw)
In-Reply-To: <20220426130444.300556-1-jean-philippe@linaro.org>
On 2022/4/26 下午9:04, Jean-Philippe Brucker wrote:
> We currently call arm64_mm_context_put() without holding a reference to
> the mm, which can result in use-after-free. Call mmgrab()/mmdrop() to
> ensure the mm only gets freed after we unpinned the ASID.
>
> Fixes: 32784a9562fb ("iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind()")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Thanks Jean
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> ---
> v2: Add missing include
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> 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..5d029e87c8af 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
> @@ -6,6 +6,7 @@
> #include <linux/mm.h>
> #include <linux/mmu_context.h>
> #include <linux/mmu_notifier.h>
> +#include <linux/sched/mm.h>
> #include <linux/slab.h>
>
> #include "arm-smmu-v3.h"
> @@ -96,9 +97,14 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
> struct arm_smmu_ctx_desc *cd;
> struct arm_smmu_ctx_desc *ret = NULL;
>
> + /* Don't free the mm until we release the ASID */
> + mmgrab(mm);
> +
> asid = arm64_mm_context_get(mm);
> - if (!asid)
> - return ERR_PTR(-ESRCH);
> + if (!asid) {
> + err = -ESRCH;
> + goto out_drop_mm;
> + }
>
> cd = kzalloc(sizeof(*cd), GFP_KERNEL);
> if (!cd) {
> @@ -165,6 +171,8 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
> kfree(cd);
> out_put_context:
> arm64_mm_context_put(mm);
> +out_drop_mm:
> + mmdrop(mm);
> return err < 0 ? ERR_PTR(err) : ret;
> }
>
> @@ -173,6 +181,7 @@ static void arm_smmu_free_shared_cd(struct arm_smmu_ctx_desc *cd)
> if (arm_smmu_free_asid(cd)) {
> /* Unpin ASID */
> arm64_mm_context_put(cd->mm);
> + mmdrop(cd->mm);
> kfree(cd);
> }
> }
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next prev parent reply other threads:[~2022-04-26 13:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 13:04 [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free Jean-Philippe Brucker
2022-04-26 13:52 ` Zhangfei Gao [this message]
2022-05-06 16:07 ` Will Deacon
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