A splat from kmem_cache_destroy() was seen with a kernel prior to
commit ee2653bbe89d ("iommu/vt-d: Remove domain and devinfo mempool")
when there was a failure in init_dmars(), because the iommu_domain
cache still had objects. While the mempool code is now gone, there
still is a leak of the si_domain memory if init_dmars() fails. So
clean up si_domain in the init_dmars() error path.

Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Fixes: 86080ccc223a ("iommu/vt-d: Allocate si_domain in init_dmars()")
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
---
v2: Set si_domain to NULL after the memory it points to has been freed.

 drivers/iommu/intel/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 31bc50e538a3..ecc0b05b2796 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2400,6 +2400,7 @@ static int __init si_domain_init(int hw)
 
 	if (md_domain_init(si_domain, DEFAULT_DOMAIN_ADDRESS_WIDTH)) {
 		domain_exit(si_domain);
+		si_domain = NULL;
 		return -EFAULT;
 	}
 
@@ -3042,6 +3043,10 @@ static int __init init_dmars(void)
 		disable_dmar_iommu(iommu);
 		free_dmar_iommu(iommu);
 	}
+	if (si_domain) {
+		domain_exit(si_domain);
+		si_domain = NULL;
+	}
 
 	return ret;
 }
-- 
2.37.2

On 10/10/22 10:48 PM, Jerry Snitselaar wrote:
> A splat from kmem_cache_destroy() was seen with a kernel prior to
> commit ee2653bbe89d ("iommu/vt-d: Remove domain and devinfo mempool")
> when there was a failure in init_dmars(), because the iommu_domain
> cache still had objects. While the mempool code is now gone, there
> still is a leak of the si_domain memory if init_dmars() fails. So
> clean up si_domain in the init_dmars() error path.
> 
> Cc: Lu Baolu<baolu.lu@linux.intel.com>
> Cc: Joerg Roedel<joro@8bytes.org>
> Cc: Will Deacon<will@kernel.org>
> Cc: Robin Murphy<robin.murphy@arm.com>
> Fixes: 86080ccc223a ("iommu/vt-d: Allocate si_domain in init_dmars()")
> Signed-off-by: Jerry Snitselaar<jsnitsel@redhat.com>

Thanks for the patch. It has been queued for v6.1.

https://lore.kernel.org/linux-iommu/20221019004447.4563-1-baolu.lu@linux.intel.com/

Best regards,
baolu