[PATCH AUTOSEL 5.4 23/24] drm/nouveau/gem: fix "refcount_t: underflow; use-after-free"

From: Sasha Levin
Date: Mon Nov 02 2020 - 20:20:41 EST


From: Karol Herbst <kherbst@xxxxxxxxxx>

[ Upstream commit 925681454d7b557d404b5d28ef4469fac1b2e105 ]

we can't use nouveau_bo_ref here as no ttm object was allocated and
nouveau_bo_ref mainly deals with that. Simply deallocate the object.

Signed-off-by: Karol Herbst <kherbst@xxxxxxxxxx>
Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_gem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 7d39d4949ee77..2dd9fcab464b1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -197,7 +197,8 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int align, uint32_t domain,
* to the caller, instead of a normal nouveau_bo ttm reference. */
ret = drm_gem_object_init(drm->dev, &nvbo->bo.base, size);
if (ret) {
- nouveau_bo_ref(NULL, &nvbo);
+ drm_gem_object_release(&nvbo->bo.base);
+ kfree(nvbo);
return ret;
}

--
2.27.0