drm/radeon/kms: drop zero length CS indirect buffers.

If userspace sends a zero length IB, it really shouldn't have bothered
so EINVAL it.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
index b843f9bdfb14..a169067efc4e 100644
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -127,17 +127,23 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data)
                                        sizeof(struct drm_radeon_cs_chunk))) {
                         return -EFAULT;
                 }
+                p->chunks[i].length_dw = user_chunk.length_dw;
+                p->chunks[i].kdata = NULL;
                 p->chunks[i].chunk_id = user_chunk.chunk_id;
+
                 if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_RELOCS) {
                         p->chunk_relocs_idx = i;
                 }
                 if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_IB) {
                         p->chunk_ib_idx = i;
+                        /* zero length IB isn't useful */
+                        if (p->chunks[i].length_dw == 0)
+                                return -EINVAL;
                 }
+
                 p->chunks[i].length_dw = user_chunk.length_dw;
                 cdata = (uint32_t *)(unsigned long)user_chunk.chunk_data;
 
-                p->chunks[i].kdata = NULL;
                 size = p->chunks[i].length_dw * sizeof(uint32_t);
                 p->chunks[i].kdata = kzalloc(size, GFP_KERNEL);
                 if (p->chunks[i].kdata == NULL) {