This code has two bugs. If kfd_topology_device_by_proximity_domain() failed on the first iteration through the loop then "cpu_link" is uninitialized and should not be dereferenced.
The second bug is that we cannot dereference a list iterator when it points to the list head. In other words, if we exit the list_for_each_entry() loop exits without hitting a break then "cpu_link" is not a valid pointer and should not be dereferenced. Fix both of these problems by setting "cpu_link" to NULL when it is invalid and non-NULL when it is valid. That makes it easier to test for valid vs invalid. Fixes: 0f28cca87e9a ("drm/amdkfd: Extend KFD device topology to surface peer-to-peer links") Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com> --- I reported these in June but never heard back. drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c index 25990bec600d..3f0a4a415907 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c @@ -1392,8 +1392,8 @@ static int kfd_build_p2p_node_entry(struct kfd_topology_device *dev, static int kfd_create_indirect_link_prop(struct kfd_topology_device *kdev, int gpu_node) { + struct kfd_iolink_properties *gpu_link, *tmp_link, *cpu_link; struct kfd_iolink_properties *props = NULL, *props2 = NULL; - struct kfd_iolink_properties *gpu_link, *cpu_link; struct kfd_topology_device *cpu_dev; int ret = 0; int i, num_cpu; @@ -1416,16 +1416,19 @@ static int kfd_create_indirect_link_prop(struct kfd_topology_device *kdev, int g continue; /* find CPU <--> CPU links */ + cpu_link = NULL; cpu_dev = kfd_topology_device_by_proximity_domain(i); if (cpu_dev) { - list_for_each_entry(cpu_link, + list_for_each_entry(tmp_link, &cpu_dev->io_link_props, list) { - if (cpu_link->node_to == gpu_link->node_to) + if (tmp_link->node_to == gpu_link->node_to) { + cpu_link = tmp_link; break; + } } } - if (cpu_link->node_to != gpu_link->node_to) + if (!cpu_link) return -ENOMEM; /* CPU <--> CPU <--> GPU, GPU node*/ -- 2.35.1