Re: [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free

2022-05-06 Thread Will Deacon 
On Tue, 26 Apr 2022 14:04:45 +0100, 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.
> 
> 

Applied to will (for-joerg/arm-smmu/updates), thanks!

[1/1] iommu/arm-smmu-v3-sva: Fix mm use-after-free
  https://git.kernel.org/will/c/cbd23144f766

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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Re: [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free

2022-04-26 Thread Zhangfei Gao 



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 


Thanks Jean

Tested-by: Zhangfei Gao 



---
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 
  #include 
  #include 
+#include 
  #include 
  
  #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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[PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free

2022-04-26 Thread Jean-Philippe Brucker 
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 
---
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 
 #include 
 #include 
+#include 
 #include 
 
 #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);
}
 }
-- 
2.35.1

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