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Patch "vfio/pci: Fix integer overflows, bitmask check" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Apr 28, 2017

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

vfio/pci: Fix integer overflows, bitmask check

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:
vfio-pci-fix-integer-overflows-bitmask-check.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 <[email protected]> know about it.

Quoted 1 line

From 05692d7005a364add85c6e25a6c4447ce08f913a Mon Sep 17 00:00:00 2001

From: Vlad Tsyrklevich <[email protected]>
Date: Wed, 12 Oct 2016 18:51:24 +0200
Subject: vfio/pci: Fix integer overflows, bitmask check

From: Vlad Tsyrklevich <[email protected]>

commit 05692d7005a364add85c6e25a6c4447ce08f913a upstream.

The VFIO_DEVICE_SET_IRQS ioctl did not sufficiently sanitize user-supplied integers, potentially allowing memory corruption. This patch adds appropriate integer overflow checks, checks the range bounds for VFIO_IRQ_SET_DATA_NONE, and also verifies that only single element in the VFIO_IRQ_SET_DATA_TYPE_MASK bitmask is set. VFIO_IRQ_SET_ACTION_TYPE_MASK is already correctly checked later in vfio_pci_set_irqs_ioctl().

Furthermore, a kzalloc is changed to a kcalloc because the use of a kzalloc with an integer multiplication allowed an integer overflow condition to be reached without this patch. kcalloc checks for overflow and should prevent a similar occurrence.

Signed-off-by Vlad Tsyrklevich <[email protected]>
Signed-off-by Alex Williamson <[email protected]>
Cc Ben Hutchings <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/vfio/pci/vfio_pci.c       |   35 ++++++++++++++++++++++-------------
 drivers/vfio/pci/vfio_pci_intrs.c |    2 +-
 2 files changed, 23 insertions(+), 14 deletions(-)
drivers/vfio/pci/vfio_pci.c +22 -13
@@ -562,8 +562,9 @@ static long vfio_pci_ioctl(void *device_
 
 	} else if (cmd == VFIO_DEVICE_SET_IRQS) {
 		struct vfio_irq_set hdr;
+		size_t size;
 		u8 *data = NULL;
-		int ret = 0;
+		int max, ret = 0;
 
 		minsz = offsetofend(struct vfio_irq_set, count);
 

@@ -571,23 +572,31 @@ static long vfio_pci_ioctl(void *device_
 			return -EFAULT;
 
 		if (hdr.argsz < minsz || hdr.index >= VFIO_PCI_NUM_IRQS ||
+		    hdr.count >= (U32_MAX - hdr.start) ||
 		    hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
 				  VFIO_IRQ_SET_ACTION_TYPE_MASK))
 			return -EINVAL;
 
-		if (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE)) {
-			size_t size;
-			int max = vfio_pci_get_irq_count(vdev, hdr.index);
-
-			if (hdr.flags & VFIO_IRQ_SET_DATA_BOOL)
-				size = sizeof(uint8_t);
-			else if (hdr.flags & VFIO_IRQ_SET_DATA_EVENTFD)
-				size = sizeof(int32_t);
-			else
-				return -EINVAL;
+		max = vfio_pci_get_irq_count(vdev, hdr.index);
+		if (hdr.start >= max || hdr.start + hdr.count > max)
+			return -EINVAL;
+
+		switch (hdr.flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
+		case VFIO_IRQ_SET_DATA_NONE:
+			size = 0;
+			break;
+		case VFIO_IRQ_SET_DATA_BOOL:
+			size = sizeof(uint8_t);
+			break;
+		case VFIO_IRQ_SET_DATA_EVENTFD:
+			size = sizeof(int32_t);
+			break;
+		default:
+			return -EINVAL;
+		}
 
-			if (hdr.argsz - minsz < hdr.count * size ||
-			    hdr.start >= max || hdr.start + hdr.count > max)
+		if (size) {
+			if (hdr.argsz - minsz < hdr.count * size)
 				return -EINVAL;
 
 			data = memdup_user((void __user *)(arg + minsz),
drivers/vfio/pci/vfio_pci_intrs.c +1 -1
@@ -255,7 +255,7 @@ static int vfio_msi_enable(struct vfio_p
 	if (!is_irq_none(vdev))
 		return -EINVAL;
 
-	vdev->ctx = kzalloc(nvec * sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
+	vdev->ctx = kcalloc(nvec, sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
 	if (!vdev->ctx)
 		return -ENOMEM;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/vfio-pci-fix-integer-overflows-bitmask-check.patch