[PATCH 4.4 13/30] s390/pci: fix use after free in dma_init

Greg Kroah-Hartman
2017-03-24T18:16:59Z

From: Sebastian Ott <sebott@linux.vnet.ibm.com>

commit dba599091c191d209b1499511a524ad9657c0e5a upstream.

After a failure during registration of the dma_table (because of the
function being in error state) we free its memory but don't reset the
associated pointer to zero.

When we then receive a notification from firmware (about the function
being in error state) we'll try to walk and free the dma_table again.

Fix this by resetting the dma_table pointer. In addition to that make
sure that we free the iommu_bitmap when appropriate.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/pci/pci_dma.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -455,7 +455,7 @@ int zpci_dma_init_device(struct zpci_dev
zdev->dma_table = dma_alloc_cpu_table();
if (!zdev->dma_table) {
rc = -ENOMEM;
- goto out_clean;
+ goto out;
}

/*
@@ -475,18 +475,22 @@ int zpci_dma_init_device(struct zpci_dev
zdev->iommu_bitmap = vzalloc(zdev->iommu_pages / 8);
if (!zdev->iommu_bitmap) {
rc = -ENOMEM;
- goto out_reg;
+ goto free_dma_table;
}

rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
(u64) zdev->dma_table);
if (rc)
- goto out_reg;
- return 0;
+ goto free_bitmap;

-out_reg:
+ return 0;
+free_bitmap:
+ vfree(zdev->iommu_bitmap);
+ zdev->iommu_bitmap = NULL;
+free_dma_table:
dma_free_cpu_table(zdev->dma_table);
-out_clean:
+ zdev->dma_table = NULL;
+out:
return rc;
}