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authorJoerg Roedel <jroedel@suse.de>2015-11-04 13:53:26 +0100
committerAlex Williamson <alex.williamson@redhat.com>2015-11-04 09:27:39 -0700
commite324fc82ea453fcbd3898ec7afb792f750c68979 (patch)
tree914d7b4679b70b623a2784cc71e5a78f1e1acbf5
parent0990822c98661bd625033f0d523b5c33566657ef (diff)
downloadlinux-e324fc82ea453fcbd3898ec7afb792f750c68979.tar.bz2
vfio: Fix bug in vfio_device_get_from_name()
The vfio_device_get_from_name() function might return a non-NULL pointer, when called with a device name that is not found in the list. This causes undefined behavior, in my case calling an invalid function pointer later on: kernel tried to execute NX-protected page - exploit attempt? (uid: 0) BUG: unable to handle kernel paging request at ffff8800cb3ddc08 [...] Call Trace: [<ffffffffa03bd733>] ? vfio_group_fops_unl_ioctl+0x253/0x410 [vfio] [<ffffffff811efc4d>] do_vfs_ioctl+0x2cd/0x4c0 [<ffffffff811f9657>] ? __fget+0x77/0xb0 [<ffffffff811efeb9>] SyS_ioctl+0x79/0x90 [<ffffffff81001bb0>] ? syscall_return_slowpath+0x50/0x130 [<ffffffff8167f776>] entry_SYSCALL_64_fastpath+0x16/0x75 Fix the issue by returning NULL when there is no device with the requested name in the list. Cc: stable@vger.kernel.org # v4.2+ Fixes: 4bc94d5dc95d ("vfio: Fix lockdep issue") Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
-rw-r--r--drivers/vfio/vfio.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 1c0f98c2f634..ab056f7af54d 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -711,11 +711,12 @@ EXPORT_SYMBOL_GPL(vfio_device_get_from_dev);
static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
char *buf)
{
- struct vfio_device *device;
+ struct vfio_device *it, *device = NULL;
mutex_lock(&group->device_lock);
- list_for_each_entry(device, &group->device_list, group_next) {
- if (!strcmp(dev_name(device->dev), buf)) {
+ list_for_each_entry(it, &group->device_list, group_next) {
+ if (!strcmp(dev_name(it->dev), buf)) {
+ device = it;
vfio_device_get(device);
break;
}