* [PATCH 1/2] drm/nouveau: Fix NULL pointer dereferences in GETPARAM ioctl
2026-08-15 17:30 [PATCH 0/2] drm/nouveau: Fix NULL pointer dereferences in GETPARAM and GET_ZCULL_INFO ioctls Jim Cromie
@ 2026-08-15 17:30 ` Jim Cromie
2026-08-15 17:30 ` [PATCH 2/2] drm/nouveau: Fix NULL pointer dereference in GET_ZCULL_INFO ioctl Jim Cromie
1 sibling, 0 replies; 3+ messages in thread
From: Jim Cromie @ 2026-08-15 17:30 UTC (permalink / raw)
To: Lyude Paul, Danilo Krummrich, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, David Airlie, Simona Vetter
Cc: dri-devel, nouveau, linux-kernel, Jim Cromie
When hardware or firmware initialization fails, the graphics engine
(gr) or device functions may remain NULL. Attempting to access these
during the GETPARAM ioctl (e.g., NOUVEAU_GETPARAM_GRAPH_UNITS) results
in a kernel NULL pointer dereference, causing a crash when userspace
(GNOME/Mesa) attempts to probe the device.
Add safety checks for 'gr', 'gr->func', and 'nvkm_device->func' in the
ioctl handler. Return -ENODEV to signal the missing hardware state to
userspace, and use NV_ERROR_ONCE to provide diagnostic proof in the
kernel log without risking a console flood.
RFC:
These crashes may not be repeatable, they happened while I was trying
to build nouveau as a builtin module, with binary blobs in the kernel
image, on a laptop with an encrypted disk. Gemini tells me this won't
work, so I punted.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/nouveau/nouveau_abi16.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_abi16.c b/drivers/gpu/drm/nouveau/nouveau_abi16.c
index 291203121f0c..c9270c5b0fac 100644
--- a/drivers/gpu/drm/nouveau/nouveau_abi16.c
+++ b/drivers/gpu/drm/nouveau/nouveau_abi16.c
@@ -306,7 +306,12 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS)
getparam->value = 1;
break;
case NOUVEAU_GETPARAM_GRAPH_UNITS:
- getparam->value = nvkm_gr_units(gr);
+ if (gr && gr->func) {
+ getparam->value = nvkm_gr_units(gr);
+ } else {
+ NV_ERROR_ONCE(drm, "GETPARAM_GRAPH_UNITS: no gr engine or func\n");
+ return -ENODEV;
+ }
break;
case NOUVEAU_GETPARAM_EXEC_PUSH_MAX: {
int ib_max = getparam_dma_ib_max(device);
@@ -315,11 +320,23 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS)
break;
}
case NOUVEAU_GETPARAM_VRAM_BAR_SIZE:
- getparam->value = nvkm_device->func->resource_size(nvkm_device, NVKM_BAR1_FB);
+ if (nvkm_device && nvkm_device->func && nvkm_device->func->resource_size) {
+ getparam->value =
+ nvkm_device->func->resource_size(nvkm_device, NVKM_BAR1_FB);
+ } else {
+ NV_ERROR_ONCE(drm, "GETPARAM_VRAM_BAR_SIZE: no device func\n");
+ return -ENODEV;
+ }
break;
case NOUVEAU_GETPARAM_VRAM_USED: {
- struct ttm_resource_manager *vram_mgr = ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM);
- getparam->value = (u64)ttm_resource_manager_usage(vram_mgr);
+ struct ttm_resource_manager *vram_mgr =
+ ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM);
+ if (vram_mgr) {
+ getparam->value = (u64)ttm_resource_manager_usage(vram_mgr);
+ } else {
+ NV_ERROR_ONCE(drm, "GETPARAM_VRAM_USED: no vram mgr\n");
+ return -ENODEV;
+ }
break;
}
case NOUVEAU_GETPARAM_HAS_VMA_TILEMODE:
--
2.55.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] drm/nouveau: Fix NULL pointer dereference in GET_ZCULL_INFO ioctl
2026-08-15 17:30 [PATCH 0/2] drm/nouveau: Fix NULL pointer dereferences in GETPARAM and GET_ZCULL_INFO ioctls Jim Cromie
2026-08-15 17:30 ` [PATCH 1/2] drm/nouveau: Fix NULL pointer dereferences in GETPARAM ioctl Jim Cromie
@ 2026-08-15 17:30 ` Jim Cromie
1 sibling, 0 replies; 3+ messages in thread
From: Jim Cromie @ 2026-08-15 17:30 UTC (permalink / raw)
To: Lyude Paul, Danilo Krummrich, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, David Airlie, Simona Vetter
Cc: dri-devel, nouveau, linux-kernel, Jim Cromie
When graphics engine firmware fails to load or initialization aborts
early, nvxx_gr(drm) returns NULL. Calling DRM_IOCTL_NOUVEAU_GET_ZCULL_INFO
causes nouveau_abi16_ioctl_get_zcull_info() to dereference gr at offset
0xf0 without checking for NULL, triggering a kernel page fault.
Validate that gr is non-NULL before inspecting gr->has_zcull_info.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
Aug 14 09:21:52 frodo kernel: BUG: kernel NULL pointer dereference, address: 00000000000000f0
Aug 14 09:21:52 frodo kernel: #PF: error_code(0x0000) - not-present page
Aug 14 09:21:52 frodo kernel: Oops: Oops: 0000 [#1] SMP NOPTI
Aug 14 09:21:52 frodo kernel: RIP: 0010:nouveau_abi16_ioctl_get_zcull_info+0x17/0xa0 [nouveau]
Aug 14 09:21:52 frodo kernel: Code: 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 48 8b 47 40 48 8b 00 48 8b 80 70 02 00 00 <80> b8 f0 00 00 00 00 74 72 8b 90 c0 00 00 00 89 16 8b 90 c4 00 00
Aug 14 09:21:52 frodo kernel: Call Trace:
Aug 14 09:21:52 frodo kernel: <TASK>
Aug 14 09:21:52 frodo kernel: drm_ioctl_kernel+0xae/0x100
Aug 14 09:21:52 frodo kernel: drm_ioctl+0x2e0/0x560
Aug 14 09:21:52 frodo kernel: ? __pfx_nouveau_abi16_ioctl_get_zcull_info+0x10/0x10 [nouveau]
Aug 14 09:21:52 frodo kernel: nouveau_drm_ioctl+0x58/0xc0 [nouveau]
Aug 14 09:21:52 frodo kernel: __x64_sys_ioctl+0xb9/0x100
Aug 14 09:21:52 frodo kernel: do_syscall_64+0xe2/0x560
Aug 14 09:21:52 frodo kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
Aug 14 09:21:52 frodo kernel: </TASK>
---
drivers/gpu/drm/nouveau/nouveau_abi16.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_abi16.c b/drivers/gpu/drm/nouveau/nouveau_abi16.c
index c9270c5b0fac..f1026a716ff7 100644
--- a/drivers/gpu/drm/nouveau/nouveau_abi16.c
+++ b/drivers/gpu/drm/nouveau/nouveau_abi16.c
@@ -357,7 +357,7 @@ nouveau_abi16_ioctl_get_zcull_info(ABI16_IOCTL_ARGS)
struct nvkm_gr *gr = nvxx_gr(drm);
struct drm_nouveau_get_zcull_info *out = data;
- if (gr->has_zcull_info) {
+ if (gr && gr->has_zcull_info) {
const struct nvkm_gr_zcull_info *i = &gr->zcull_info;
out->width_align_pixels = i->width_align_pixels;
--
2.55.0
^ permalink raw reply related [flat|nested] 3+ messages in thread