[PATCH v1] iommu/ipmmu-vmsa: Set context_id to non-existent value if allocation failed

[Oleksandr Tyshchenko]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko at epam.com>

In ipmmu_domain_init_context() we are trying to allocate context and
if allocation fails we will call free_io_pgtable_ops(),
but "domain->context_id" hasn't been initialized yet (likely it is 0
because of kzalloc). Having the following call stack:
free_io_pgtable_ops() -> io_pgtable_tlb_flush_all() ->
ipmmu_tlb_flush_all() -> ipmmu_tlb_invalidate()
we will get a mistaken cache flush for a context pointed by
uninitialized "domain->context_id".

So, set context_id to non-existent value (IPMMU_CTX_MAX) before calling
free_io_pgtable_ops() and check it for a valid value (< IPMMU_CTX_MAX)
before calling ipmmu_tlb_invalidate().

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko at epam.com>
---
 drivers/iommu/ipmmu-vmsa.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 2a38aa1..5b226c0 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -303,6 +303,9 @@ static void ipmmu_tlb_flush_all(void *cookie)
 {
 	struct ipmmu_vmsa_domain *domain = cookie;
 
+	if (domain->context_id >= IPMMU_CTX_MAX)
+		return;
+
 	ipmmu_tlb_invalidate(domain);
 }
 
@@ -380,6 +383,7 @@ static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
 	 */
 	ret = ipmmu_domain_allocate_context(domain->mmu, domain);
 	if (ret == IPMMU_CTX_MAX) {
+		domain->context_id = IPMMU_CTX_MAX;
 		free_io_pgtable_ops(domain->iop);
 		return -EBUSY;
 	}
-- 
2.7.4