From: Jean-Philippe Brucker jean-philippe@linaro.org
[ Upstream commit cbd23144f7662b00bcde32a938c4a4057e476d68 ]
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 Tested-by: Zhangfei Gao zhangfei.gao@linaro.org Link: https://lore.kernel.org/r/20220426130444.300556-1-jean-philippe@linaro.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 f763c1430d15..e2e80eb2840c 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); } }