From e324fc82ea453fcbd3898ec7afb792f750c68979 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 4 Nov 2015 13:53:26 +0100 Subject: [PATCH] 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: [] ? vfio_group_fops_unl_ioctl+0x253/0x410 [vfio] [] do_vfs_ioctl+0x2cd/0x4c0 [] ? __fget+0x77/0xb0 [] SyS_ioctl+0x79/0x90 [] ? syscall_return_slowpath+0x50/0x130 [] 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 Signed-off-by: Alex Williamson --- drivers/vfio/vfio.c | 7 ++++--- 1 file 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; }