[PATCH] ram/gf100-: error out if a ridiculous amount of vram is detected

[Ilia Mirkin]

Some newer chips have trouble coming up, and we get bad MMIO reads from
them, like 0xbadf100. This ends up translating into crazy amounts of
VRAM, which destroys all sorts of other logic down the line. Instead,
fail device init.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
Cc: stable at kernel.org
---
 drm/nouveau/nvkm/subdev/fb/ramgf100.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drm/nouveau/nvkm/subdev/fb/ramgf100.c b/drm/nouveau/nvkm/subdev/fb/ramgf100.c
index de9f395..9d4d196 100644
--- a/drm/nouveau/nvkm/subdev/fb/ramgf100.c
+++ b/drm/nouveau/nvkm/subdev/fb/ramgf100.c
@@ -545,6 +545,12 @@ gf100_ram_create_(struct nvkm_object *parent, struct nvkm_object *engine,
 		}
 	}
 
+	/* if over 1TB of VRAM is reported, something went very wrong, bail */
+	if (ram->size > (1ULL << 40)) {
+		nv_error(pfb, "invalid vram size: %llx\n", ram->size);
+		return -EINVAL;
+	}
+
 	/* if all controllers have the same amount attached, there's no holes */
 	if (uniform) {
 		offset = rsvd_head;
-- 
2.3.6