[PATCH] drm/nouveau: Fix out-of-bounds access when deferencing MMU type

[Ruhl, Michael J]

>-----Original Message-----
>From: Thomas Zimmermann <tzimmermann at suse.de>
>Sent: Tuesday, November 10, 2020 8:37 AM
>To: bskeggs at redhat.com; airlied at linux.ie; daniel at ffwll.ch; Ruhl, Michael J
><michael.j.ruhl at intel.com>; christian.koenig at amd.com
>Cc: nouveau at lists.freedesktop.org; dri-devel at lists.freedesktop.org; Thomas
>Zimmermann <tzimmermann at suse.de>; Maarten Lankhorst
><maarten.lankhorst at linux.intel.com>; Maxime Ripard
><mripard at kernel.org>; Dave Airlie <airlied at redhat.com>; Gerd Hoffmann
><kraxel at redhat.com>; Alex Deucher <alexander.deucher at amd.com>;
>VMware Graphics <linux-graphics-maintainer at vmware.com>; Roland
>Scheidegger <sroland at vmware.com>; Huang Rui <ray.huang at amd.com>;
>Felix Kuehling <Felix.Kuehling at amd.com>; Hawking Zhang
><Hawking.Zhang at amd.com>; Jason Gunthorpe <jgg at ziepe.ca>; Likun Gao
><Likun.Gao at amd.com>; virtualization at lists.linux-foundation.org; spice-
>devel at lists.freedesktop.org; amd-gfx at lists.freedesktop.org
>Subject: [PATCH] drm/nouveau: Fix out-of-bounds access when deferencing
>MMU type
>
>The value of struct drm_device.ttm.type_vram can become -1 for unknown
>types of memory (see nouveau_ttm_init()). This leads to an out-of-bounds
>error when accessing struct nvif_mmu.type[]:

Would this make more sense to just set the type_vram = 0 instead of -1?

Mike

>
>  [   18.304116]
>===========================================================
>=======
>  [   18.311649] BUG: KASAN: slab-out-of-bounds in
>nouveau_ttm_io_mem_reserve+0x17a/0x7e0 [nouveau]
>  [   18.320415] Read of size 1 at addr ffff88810ffac1fe by task systemd-
>udevd/342
>  [   18.327681]
>  [   18.329208] CPU: 1 PID: 342 Comm: systemd-udevd Tainted: G            E
>5.10.0-rc2-1-default+ #581
>  [   18.338681] Hardware name: Dell Inc. OptiPlex 9020/0N4YC8, BIOS A24
>10/24/2018
>  [   18.346032] Call Trace:
>  [   18.348536]  dump_stack+0xae/0xe5
>  [   18.351919]  print_address_description.constprop.0+0x17/0xf0
>  [   18.357787]  ? nouveau_ttm_io_mem_reserve+0x17a/0x7e0 [nouveau]
>  [   18.363818]  __kasan_report.cold+0x20/0x38
>  [   18.368099]  ? nouveau_ttm_io_mem_reserve+0x17a/0x7e0 [nouveau]
>  [   18.374133]  kasan_report+0x3a/0x50
>  [   18.377789]  nouveau_ttm_io_mem_reserve+0x17a/0x7e0 [nouveau]
>  <...>
>  [   18.767690] Allocated by task 342:
>  [   18.773087]  kasan_save_stack+0x1b/0x40
>  [   18.778890]  __kasan_kmalloc.constprop.0+0xbf/0xd0
>  [   18.785646]  __kmalloc_track_caller+0x1be/0x390
>  [   18.792165]  kstrdup_const+0x46/0x70
>  [   18.797686]  kobject_set_name_vargs+0x2f/0xb0
>  [   18.803992]  kobject_init_and_add+0x9d/0xf0
>  [   18.810117]  ttm_mem_global_init+0x12c/0x210 [ttm]
>  [   18.816853]  ttm_bo_global_init+0x4a/0x160 [ttm]
>  [   18.823420]  ttm_bo_device_init+0x39/0x220 [ttm]
>  [   18.830046]  nouveau_ttm_init+0x2c3/0x830 [nouveau]
>  [   18.836929]  nouveau_drm_device_init+0x1b4/0x3f0 [nouveau]
>  <...>
>  [   19.105336]
>===========================================================
>=======
>
>Fix this error, by not using type_vram as an index if it's negative.
>Assume default values instead.
>
>The error was seen on Nvidia G72 hardware.
>
>Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>Fixes: 1cf65c45183a ("drm/ttm: add caching state to ttm_bus_placement")
>Cc: Christian König <christian.koenig at amd.com>
>Cc: Michael J. Ruhl <michael.j.ruhl at intel.com>
>Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>Cc: Maxime Ripard <mripard at kernel.org>
>Cc: Thomas Zimmermann <tzimmermann at suse.de>
>Cc: David Airlie <airlied at linux.ie>
>Cc: Daniel Vetter <daniel at ffwll.ch>
>Cc: Ben Skeggs <bskeggs at redhat.com>
>Cc: Dave Airlie <airlied at redhat.com>
>Cc: Gerd Hoffmann <kraxel at redhat.com>
>Cc: Alex Deucher <alexander.deucher at amd.com>
>Cc: "Christian König" <christian.koenig at amd.com>
>Cc: VMware Graphics <linux-graphics-maintainer at vmware.com>
>Cc: Roland Scheidegger <sroland at vmware.com>
>Cc: Huang Rui <ray.huang at amd.com>
>Cc: Felix Kuehling <Felix.Kuehling at amd.com>
>Cc: Hawking Zhang <Hawking.Zhang at amd.com>
>Cc: Jason Gunthorpe <jgg at ziepe.ca>
>Cc: Likun Gao <Likun.Gao at amd.com>
>Cc: dri-devel at lists.freedesktop.org
>Cc: nouveau at lists.freedesktop.org
>Cc: virtualization at lists.linux-foundation.org
>Cc: spice-devel at lists.freedesktop.org
>Cc: amd-gfx at lists.freedesktop.org
>---
> drivers/gpu/drm/nouveau/nouveau_bo.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
>b/drivers/gpu/drm/nouveau/nouveau_bo.c
>index 8133377d865d..fe15299d417e 100644
>--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
>+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
>@@ -1142,9 +1142,12 @@ nouveau_ttm_io_mem_reserve(struct
>ttm_bo_device *bdev, struct ttm_resource *reg)
> 	struct nvkm_device *device = nvxx_device(&drm->client.device);
> 	struct nouveau_mem *mem = nouveau_mem(reg);
> 	struct nvif_mmu *mmu = &drm->client.mmu;
>-	const u8 type = mmu->type[drm->ttm.type_vram].type;
>+	u8 type = 0;
> 	int ret;
>
>+	if (drm->ttm.type_vram >= 0)
>+		type = mmu->type[drm->ttm.type_vram].type;
>+
> 	mutex_lock(&drm->ttm.io_reserve_mutex);
> retry:
> 	switch (reg->mem_type) {
>--
>2.29.2