Patch "s390/pci: fix use after free in dma_init" has been added to the 4.4-stable tree

Patch "s390/pci: fix use after free in dma_init" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    s390/pci: fix use after free in dma_init

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-pci-fix-use-after-free-in-dma_init.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From dba599091c191d209b1499511a524ad9657c0e5a Mon Sep 17 00:00:00 2001
From: Sebastian Ott <sebott@linux.vnet.ibm.com>
Date: Fri, 15 Apr 2016 09:41:35 +0200
Subject: s390/pci: fix use after free in dma_init

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;
 }
 


Patches currently in stable-queue which might be from sebott@linux.vnet.ibm.com are

queue-4.4/s390-pci-fix-use-after-free-in-dma_init.patch