The code expects non-VRAM mem nodes to have a pages list. If that's not set, it will do a null deref down the line. Warn on that condition and return an error.
See https://bugs.freedesktop.org/show_bug.cgi?id=64774 Reported-by: Pasi K?rkk?inen <pasik at iki.fi> Tested-by: Pasi K?rkk?inen <pasik at iki.fi> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu> Cc: <stable at vger.kernel.org> # 3.8+ --- I don't exactly understand what's going on, but this is just a straightforward way to avoid a null deref that you see happens in the bug. I haven't figured out the root cause of this, but it's getting well into the "I have no idea how TTM works" space. However this seems like a bit of defensive programming -- nouveau_vm_map_sg will pass node->pages as a list down, which will be dereferenced by nvc0_vm_map_sg. Perhaps the other arguments should make that dereferencing not happen, but it definitely was happening here, as you can see in the bug. Ben/Maarten, I'll let you judge whether this check is appropriate, since like I hope I was able to convey above, I'm just not really sure :) drivers/gpu/drm/nouveau/nouveau_bo.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c index cdc3282..191145d 100644 --- a/drivers/gpu/drm/nouveau/nouveau_bo.c +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c @@ -963,6 +963,12 @@ nouveau_vma_getmap(struct nouveau_channel *chan, struct nouveau_bo *nvbo, struct nouveau_mem *node = mem->mm_node; int ret; + /* If we ever get here for a non-vram mem node that doesn't + * have pages, we will end up doing a null deref in + * nouveau_vm_map_sg. */ + if (WARN_ON(mem->mem_type != TTM_PL_VRAM && !node->pages)) + return -EINVAL; + ret = nouveau_vm_get(nv_client(chan->cli)->vm, mem->num_pages << PAGE_SHIFT, node->page_shift, NV_MEM_ACCESS_RW, vma); -- 1.8.1.5
