[PATCH v2 0/2] virtio-gpu: coverity fixes

[PATCH v2 0/2] virtio-gpu: coverity fixes

[Alex Bennée]

v2,

Fixes after Dimitry's review.

Alex.

Alex Bennée (2):
  hw/display: factor out the scanout blob to fb conversion
  hw/display: check frame buffer can hold blob

 include/hw/virtio/virtio-gpu.h | 15 +++++++++
 hw/display/virtio-gpu-virgl.c  | 22 +------------
 hw/display/virtio-gpu.c        | 59 +++++++++++++++++++++-------------
 3 files changed, 52 insertions(+), 44 deletions(-)

-- 
2.39.5

[PATCH v2 1/2] hw/display: factor out the scanout blob to fb conversion

[Alex Bennée]

There are two identical sequences of a code doing the same thing that
raise warnings with Coverity. Before fixing those issues lets factor
out the common code into a helper function we can share.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>

---
v2
  - fix compile of virtio-gpu-virgl
  - tweak comment for blob_size
---
 include/hw/virtio/virtio-gpu.h | 15 +++++++++
 hw/display/virtio-gpu-virgl.c  | 22 +------------
 hw/display/virtio-gpu.c        | 60 +++++++++++++++++++++-------------
 3 files changed, 53 insertions(+), 44 deletions(-)

diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 553799b8cc..924eb8737e 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -333,6 +333,21 @@ void virtio_gpu_update_cursor_data(VirtIOGPU *g,
                                    struct virtio_gpu_scanout *s,
                                    uint32_t resource_id);
 
+/**
+ * virtio_gpu_scanout_blob_to_fb() - fill out fb based on scanout data
+ * fb: the frame-buffer descriptor to fill out
+ * ss: the scanout blob data
+ * blob_size: size of scanout blob data
+ *
+ * This will check we have enough space for the frame taking into
+ * account that stride for all but the last line.
+ *
+ * Returns true on success, otherwise logs guest error and returns false
+ */
+bool virtio_gpu_scanout_blob_to_fb(struct virtio_gpu_framebuffer *fb,
+                                   struct virtio_gpu_set_scanout_blob *ss,
+                                   uint64_t blob_size);
+
 /* virtio-gpu-udmabuf.c */
 bool virtio_gpu_have_udmabuf(void);
 void virtio_gpu_init_udmabuf(struct virtio_gpu_simple_resource *res);
diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c
index eedae7357f..145a0b3879 100644
--- a/hw/display/virtio-gpu-virgl.c
+++ b/hw/display/virtio-gpu-virgl.c
@@ -805,7 +805,6 @@ static void virgl_cmd_set_scanout_blob(VirtIOGPU *g,
     struct virtio_gpu_framebuffer fb = { 0 };
     struct virtio_gpu_virgl_resource *res;
     struct virtio_gpu_set_scanout_blob ss;
-    uint64_t fbend;
 
     VIRTIO_GPU_FILL_CMD(ss);
     virtio_gpu_scanout_blob_bswap(&ss);
@@ -852,26 +851,7 @@ static void virgl_cmd_set_scanout_blob(VirtIOGPU *g,
         return;
     }
 
-    fb.format = virtio_gpu_get_pixman_format(ss.format);
-    if (!fb.format) {
-        qemu_log_mask(LOG_GUEST_ERROR, "%s: pixel format not supported %d\n",
-                      __func__, ss.format);
-        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
-        return;
-    }
-
-    fb.bytes_pp = DIV_ROUND_UP(PIXMAN_FORMAT_BPP(fb.format), 8);
-    fb.width = ss.width;
-    fb.height = ss.height;
-    fb.stride = ss.strides[0];
-    fb.offset = ss.offsets[0] + ss.r.x * fb.bytes_pp + ss.r.y * fb.stride;
-
-    fbend = fb.offset;
-    fbend += fb.stride * (ss.r.height - 1);
-    fbend += fb.bytes_pp * ss.r.width;
-    if (fbend > res->base.blob_size) {
-        qemu_log_mask(LOG_GUEST_ERROR, "%s: fb end out of range\n",
-                      __func__);
+    if (!virtio_gpu_scanout_blob_to_fb(&fb, &ss, res->base.blob_size)) {
         cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
         return;
     }
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index c0570ef856..e7ca8fd1cf 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -721,13 +721,48 @@ static void virtio_gpu_set_scanout(VirtIOGPU *g,
                               &fb, res, &ss.r, &cmd->error);
 }
 
+bool virtio_gpu_scanout_blob_to_fb(struct virtio_gpu_framebuffer *fb,
+                                   struct virtio_gpu_set_scanout_blob *ss,
+                                   uint64_t blob_size)
+{
+    uint64_t fbend;
+
+    fb->format = virtio_gpu_get_pixman_format(ss->format);
+    if (!fb->format) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: host couldn't handle guest format %d\n",
+                      __func__, ss->format);
+        return false;
+    }
+
+    fb->bytes_pp = DIV_ROUND_UP(PIXMAN_FORMAT_BPP(fb->format), 8);
+    fb->width = ss->width;
+    fb->height = ss->height;
+    fb->stride = ss->strides[0];
+    fb->offset = ss->offsets[0] + ss->r.x * fb->bytes_pp + ss->r.y * fb->stride;
+
+    fbend = fb->offset;
+    fbend += fb->stride * (ss->r.height - 1);
+    fbend += fb->bytes_pp * ss->r.width;
+
+    if (fbend > blob_size) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: fb end out of range\n",
+                      __func__);
+        return false;
+    }
+
+    return true;
+}
+
+
+
 static void virtio_gpu_set_scanout_blob(VirtIOGPU *g,
                                         struct virtio_gpu_ctrl_command *cmd)
 {
     struct virtio_gpu_simple_resource *res;
     struct virtio_gpu_framebuffer fb = { 0 };
     struct virtio_gpu_set_scanout_blob ss;
-    uint64_t fbend;
 
     VIRTIO_GPU_FILL_CMD(ss);
     virtio_gpu_scanout_blob_bswap(&ss);
@@ -753,28 +788,7 @@ static void virtio_gpu_set_scanout_blob(VirtIOGPU *g,
         return;
     }
 
-    fb.format = virtio_gpu_get_pixman_format(ss.format);
-    if (!fb.format) {
-        qemu_log_mask(LOG_GUEST_ERROR,
-                      "%s: host couldn't handle guest format %d\n",
-                      __func__, ss.format);
-        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
-        return;
-    }
-
-    fb.bytes_pp = DIV_ROUND_UP(PIXMAN_FORMAT_BPP(fb.format), 8);
-    fb.width = ss.width;
-    fb.height = ss.height;
-    fb.stride = ss.strides[0];
-    fb.offset = ss.offsets[0] + ss.r.x * fb.bytes_pp + ss.r.y * fb.stride;
-
-    fbend = fb.offset;
-    fbend += fb.stride * (ss.r.height - 1);
-    fbend += fb.bytes_pp * ss.r.width;
-    if (fbend > res->blob_size) {
-        qemu_log_mask(LOG_GUEST_ERROR,
-                      "%s: fb end out of range\n",
-                      __func__);
+    if (!virtio_gpu_scanout_blob_to_fb(&fb, &ss, res->blob_size)) {
         cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
         return;
     }
-- 
2.39.5

Re: [PATCH v2 1/2] hw/display: factor out the scanout blob to fb conversion

[Dmitry Osipenko]

On 11/12/24 02:00, Alex Bennée wrote:
> There are two identical sequences of a code doing the same thing that
> raise warnings with Coverity. Before fixing those issues lets factor
> out the common code into a helper function we can share.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> 
> ---
> v2
>   - fix compile of virtio-gpu-virgl
>   - tweak comment for blob_size
> ---
>  include/hw/virtio/virtio-gpu.h | 15 +++++++++
>  hw/display/virtio-gpu-virgl.c  | 22 +------------
>  hw/display/virtio-gpu.c        | 60 +++++++++++++++++++++-------------
>  3 files changed, 53 insertions(+), 44 deletions(-)

...
> +    return true;
> +}
> +
> +
> +
>  static void virtio_gpu_set_scanout_blob(VirtIOGPU *g,

Super-nit: the extra newlines are still there. You may edit them when
applying, otherwise we can live with them for now too :)

Thanks for addressing rest of the v1 comments!

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

-- 
Best regards,
Dmitry

[PATCH v2 2/2] hw/display: check frame buffer can hold blob

[Alex Bennée]

Coverity reports (CID 1564769, 1564770) that we potentially overflow
by doing some 32x32 multiplies for something that ends up in a 64 bit
value. Fix this by first using stride for all lines and casting input
to uint64_t to ensure a 64 bit multiply is used.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>

---
v2
  - just use stride * height
  - tweak comment
---
 include/hw/virtio/virtio-gpu.h | 2 +-
 hw/display/virtio-gpu.c        | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 924eb8737e..8c977beebd 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -340,7 +340,7 @@ void virtio_gpu_update_cursor_data(VirtIOGPU *g,
  * blob_size: size of scanout blob data
  *
  * This will check we have enough space for the frame taking into
- * account that stride for all but the last line.
+ * account that stride.
  *
  * Returns true on success, otherwise logs guest error and returns false
  */
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index e7ca8fd1cf..7d22d03bbf 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -742,8 +742,7 @@ bool virtio_gpu_scanout_blob_to_fb(struct virtio_gpu_framebuffer *fb,
     fb->offset = ss->offsets[0] + ss->r.x * fb->bytes_pp + ss->r.y * fb->stride;
 
     fbend = fb->offset;
-    fbend += fb->stride * (ss->r.height - 1);
-    fbend += fb->bytes_pp * ss->r.width;
+    fbend += (uint64_t) fb->stride * ss->r.height;
 
     if (fbend > blob_size) {
         qemu_log_mask(LOG_GUEST_ERROR,
-- 
2.39.5

Re: [PATCH v2 2/2] hw/display: check frame buffer can hold blob

[Dmitry Osipenko]

On 11/12/24 02:00, Alex Bennée wrote:
> Coverity reports (CID 1564769, 1564770) that we potentially overflow
> by doing some 32x32 multiplies for something that ends up in a 64 bit
> value. Fix this by first using stride for all lines and casting input
> to uint64_t to ensure a 64 bit multiply is used.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

-- 
Best regards,
Dmitry

Re: [PATCH v2 0/2] virtio-gpu: coverity fixes

[Michael S. Tsirkin]

On Mon, Nov 11, 2024 at 11:00:38PM +0000, Alex Bennée wrote:
> v2,
> 
> Fixes after Dimitry's review.


You should CC Gerd.

> Alex.
> 
> Alex Bennée (2):
>   hw/display: factor out the scanout blob to fb conversion
>   hw/display: check frame buffer can hold blob
> 
>  include/hw/virtio/virtio-gpu.h | 15 +++++++++
>  hw/display/virtio-gpu-virgl.c  | 22 +------------
>  hw/display/virtio-gpu.c        | 59 +++++++++++++++++++++-------------
>  3 files changed, 52 insertions(+), 44 deletions(-)
> 
> -- 
> 2.39.5

Re: [PATCH v2 0/2] virtio-gpu: coverity fixes

[Alex Bennée]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Mon, Nov 11, 2024 at 11:00:38PM +0000, Alex Bennée wrote:
>> v2,
>> 
>> Fixes after Dimitry's review.
>
>
> You should CC Gerd.

Since 2f8cd5a9b6 (MAINTAINERS: drop virtio-gpu maintainership)
virtio-gpu is currently orphaned for maintainers. I've been reaching out
to various teams with GPU experience (including Dimitry) to see if we
can find a replacement maintainer. For now I'm happy to test and
upstream odd fixes.

>
>> Alex.
>> 
>> Alex Bennée (2):
>>   hw/display: factor out the scanout blob to fb conversion
>>   hw/display: check frame buffer can hold blob
>> 
>>  include/hw/virtio/virtio-gpu.h | 15 +++++++++
>>  hw/display/virtio-gpu-virgl.c  | 22 +------------
>>  hw/display/virtio-gpu.c        | 59 +++++++++++++++++++++-------------
>>  3 files changed, 52 insertions(+), 44 deletions(-)
>> 
>> -- 
>> 2.39.5

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro