From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org
Cc: zhangfei.gao@linaro.org, iommu@lists.linux-foundation.org,
Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free
Date: Tue, 26 Apr 2022 14:04:45 +0100 [thread overview]
Message-ID: <20220426130444.300556-1-jean-philippe@linaro.org> (raw)
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>
---
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);
}
}
--
2.35.1
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next reply other threads:[~2022-04-26 13:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 13:04 Jean-Philippe Brucker [this message]
2022-04-26 13:52 ` [PATCH v2] iommu/arm-smmu-v3-sva: Fix mm use-after-free Zhangfei Gao
2022-05-06 16:07 ` Will Deacon
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