| From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 082/211] vfio: Fix bug in vfio_device_get_from_name() | Date | Tue, 5 Jan 2016 11:43:10 -0800 |
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4.2.8-ckt1 -stable review patch. If anyone has any objections, please let me know.
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From: Joerg Roedel <jroedel@suse.de>
commit e324fc82ea453fcbd3898ec7afb792f750c68979 upstream.
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.
Fixes: 4bc94d5dc95d ("vfio: Fix lockdep issue") Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- 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 563c510..8c50ea6 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -692,11 +692,12 @@ 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; } -- 1.9.1
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