[PATCH 6.6 013/396] drm/vmwgfx: Fix possible null pointer derefence with invalid contexts

Greg Kroah-Hartman
2024-04-01T16:35:16Z

From: Zack Rusin <zack.rusin@broadcom.com>

[ Upstream commit 517621b7060096e48e42f545fa6646fc00252eac ]

vmw_context_cotable can return either an error or a null pointer and its
usage sometimes went unchecked. Subsequent code would then try to access
either a null pointer or an error value.

The invalid dereferences were only possible with malformed userspace
apps which never properly initialized the rendering contexts.

Check the results of vmw_context_cotable to fix the invalid derefs.

Thanks:
ziming zhang(@ezrak1e) from Ant Group Light-Year Security Lab
who was the first person to discover it.
Niels De Graef who reported it and helped to track down the poc.

Fixes: 9c079b8ce8bf ("drm/vmwgfx: Adapt execbuf to the new validation api")
Cc: <stable@vger.kernel.org> # v4.20+
Reported-by: Niels De Graef <ndegraef@redhat.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Cc: Martin Krastev <martin.krastev@broadcom.com>
Cc: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
Cc: Ian Forbes <ian.forbes@broadcom.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240110200305.94086-1-zack.rusin@broadcom.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index 36987ef3fc300..5fef0b31c1179 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -447,7 +447,7 @@ static int vmw_resource_context_res_add(struct vmw_private *dev_priv,
vmw_res_type(ctx) == vmw_res_dx_context) {
for (i = 0; i < cotable_max; ++i) {
res = vmw_context_cotable(ctx, i);
- if (IS_ERR(res))
+ if (IS_ERR_OR_NULL(res))
continue;

ret = vmw_execbuf_res_val_add(sw_context, res,
@@ -1266,6 +1266,8 @@ static int vmw_cmd_dx_define_query(struct vmw_private *dev_priv,
return -EINVAL;

cotable_res = vmw_context_cotable(ctx_node->ctx, SVGA_COTABLE_DXQUERY);
+ if (IS_ERR_OR_NULL(cotable_res))
+ return cotable_res ? PTR_ERR(cotable_res) : -EINVAL;
ret = vmw_cotable_notify(cotable_res, cmd->body.queryId);

return ret;
@@ -2484,6 +2486,8 @@ static int vmw_cmd_dx_view_define(struct vmw_private *dev_priv,
return ret;

res = vmw_context_cotable(ctx_node->ctx, vmw_view_cotables[view_type]);
+ if (IS_ERR_OR_NULL(res))
+ return res ? PTR_ERR(res) : -EINVAL;
ret = vmw_cotable_notify(res, cmd->defined_id);
if (unlikely(ret != 0))
return ret;
@@ -2569,8 +2573,8 @@ static int vmw_cmd_dx_so_define(struct vmw_private *dev_priv,

so_type = vmw_so_cmd_to_type(header->id);
res = vmw_context_cotable(ctx_node->ctx, vmw_so_cotables[so_type]);
- if (IS_ERR(res))
- return PTR_ERR(res);
+ if (IS_ERR_OR_NULL(res))
+ return res ? PTR_ERR(res) : -EINVAL;
cmd = container_of(header, typeof(*cmd), header);
ret = vmw_cotable_notify(res, cmd->defined_id);

@@ -2689,6 +2693,8 @@ static int vmw_cmd_dx_define_shader(struct vmw_private *dev_priv,
return -EINVAL;

res = vmw_context_cotable(ctx_node->ctx, SVGA_COTABLE_DXSHADER);
+ if (IS_ERR_OR_NULL(res))
+ return res ? PTR_ERR(res) : -EINVAL;
ret = vmw_cotable_notify(res, cmd->body.shaderId);
if (ret)
return ret;
@@ -3010,6 +3016,8 @@ static int vmw_cmd_dx_define_streamoutput(struct vmw_private *dev_priv,
}

res = vmw_context_cotable(ctx_node->ctx, SVGA_COTABLE_STREAMOUTPUT);
+ if (IS_ERR_OR_NULL(res))
+ return res ? PTR_ERR(res) : -EINVAL;
ret = vmw_cotable_notify(res, cmd->body.soid);
if (ret)
return ret;
--
2.43.0