Re: [PATCH] iommu/dma: Fix race condition during iova_domain initialization

From: Joerg Roedel
Date: Wed Jun 22 2022 - 08:46:32 EST


Please re-send with

Robin Murphy <robin.murphy@xxxxxxx>

in Cc.

On Mon, May 30, 2022 at 08:07:45PM +0800, yf.wang@xxxxxxxxxxxx wrote:
> From: Yunfei Wang <yf.wang@xxxxxxxxxxxx>
>
> When many devices share the same iova domain, iommu_dma_init_domain()
> may be called at the same time. The checking of iovad->start_pfn will
> all get false in iommu_dma_init_domain() and both enter init_iova_domain()
> to do iovad initialization.
>
> Fix this by protecting init_iova_domain() with iommu_dma_cookie->mutex.
>
> Exception backtrace:
> rb_insert_color(param1=0xFFFFFF80CD2BDB40, param3=1) + 64
> init_iova_domain() + 180
> iommu_setup_dma_ops() + 260
> arch_setup_dma_ops() + 132
> of_dma_configure_id() + 468
> platform_dma_configure() + 32
> really_probe() + 1168
> driver_probe_device() + 268
> __device_attach_driver() + 524
> __device_attach() + 524
> bus_probe_device() + 64
> deferred_probe_work_func() + 260
> process_one_work() + 580
> worker_thread() + 1076
> kthread() + 332
> ret_from_fork() + 16
>
> Signed-off-by: Ning Li <ning.li@xxxxxxxxxxxx>
> Signed-off-by: Yunfei Wang <yf.wang@xxxxxxxxxxxx>
> ---
> drivers/iommu/dma-iommu.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 09f6e1c0f9c0..b38c5041eeab 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -63,6 +63,7 @@ struct iommu_dma_cookie {
>
> /* Domain for flush queue callback; NULL if flush queue not in use */
> struct iommu_domain *fq_domain;
> + struct mutex mutex;
> };
>
> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
> @@ -309,6 +310,7 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
> if (!domain->iova_cookie)
> return -ENOMEM;
>
> + mutex_init(&domain->iova_cookie->mutex);
> return 0;
> }
>
> @@ -549,26 +551,33 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
> }
>
> /* start_pfn is always nonzero for an already-initialised domain */
> + mutex_lock(&cookie->mutex);
> if (iovad->start_pfn) {
> if (1UL << order != iovad->granule ||
> base_pfn != iovad->start_pfn) {
> pr_warn("Incompatible range for DMA domain\n");
> - return -EFAULT;
> + ret = -EFAULT;
> + goto done_unlock;
> }
>
> - return 0;
> + ret = 0;
> + goto done_unlock;
> }
>
> init_iova_domain(iovad, 1UL << order, base_pfn);
> ret = iova_domain_init_rcaches(iovad);
> if (ret)
> - return ret;
> + goto done_unlock;
>
> /* If the FQ fails we can simply fall back to strict mode */
> if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
> domain->type = IOMMU_DOMAIN_DMA;
>
> - return iova_reserve_iommu_regions(dev, domain);
> + ret = iova_reserve_iommu_regions(dev, domain);
> +
> +done_unlock:
> + mutex_unlock(&cookie->mutex);
> + return ret;
> }
>
> /**
> --
> 2.18.0