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iommu/arm-smmu-v3-sva: Fix mm use-after-free

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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: 32784a9562 ("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>
This commit is contained in:
Jean-Philippe Brucker 2022-04-26 14:04:45 +01:00 committed by Will Deacon
parent b131fa8c1d
commit cbd23144f7
1 changed files with 11 additions and 2 deletions
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13
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
View file

@ -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);
}
}