hw/audio/virtio-snd: fix invalid param check

[PATCH] hw/audio/virtio-snd: fix invalid param check

Posted by Volker Rümelin 3 months, 3 weeks ago

Commit 9b6083465f ("virtio-snd: check for invalid param shift
operands") tries to prevent invalid parameters specified by the
guest. However, the code is not correct.

Change the code so that the parameters format and rate, which are
a bit numbers, are compared with the bit size of the data type.

Fixes: 9b6083465f ("virtio-snd: check for invalid param shift operands")
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
 hw/audio/virtio-snd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
index e5196aa4bb..d1cf5eb445 100644
--- a/hw/audio/virtio-snd.c
+++ b/hw/audio/virtio-snd.c
@@ -282,12 +282,12 @@ uint32_t virtio_snd_set_pcm_params(VirtIOSound *s,
         error_report("Number of channels is not supported.");
         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
     }
-    if (BIT(params->format) > sizeof(supported_formats) ||
+    if (params->format >= sizeof(supported_formats) * BITS_PER_BYTE ||
         !(supported_formats & BIT(params->format))) {
         error_report("Stream format is not supported.");
         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
     }
-    if (BIT(params->rate) > sizeof(supported_rates) ||
+    if (params->rate >= sizeof(supported_rates) * BITS_PER_BYTE ||
         !(supported_rates & BIT(params->rate))) {
         error_report("Stream rate is not supported.");
         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
-- 
2.35.3

Re: [PATCH] hw/audio/virtio-snd: fix invalid param check

Posted by Manos Pitsidianakis 3 months, 3 weeks ago

On Fri, 02 Aug 2024 10:18, Volker Rümelin <vr_qemu@t-online.de> wrote:
>Commit 9b6083465f ("virtio-snd: check for invalid param shift
>operands") tries to prevent invalid parameters specified by the
>guest. However, the code is not correct.
>
>Change the code so that the parameters format and rate, which are
>a bit numbers, are compared with the bit size of the data type.
>
>Fixes: 9b6083465f ("virtio-snd: check for invalid param shift operands")
>Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
>---
> hw/audio/virtio-snd.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
>index e5196aa4bb..d1cf5eb445 100644
>--- a/hw/audio/virtio-snd.c
>+++ b/hw/audio/virtio-snd.c
>@@ -282,12 +282,12 @@ uint32_t virtio_snd_set_pcm_params(VirtIOSound *s,
>         error_report("Number of channels is not supported.");
>         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
>     }
>-    if (BIT(params->format) > sizeof(supported_formats) ||
>+    if (params->format >= sizeof(supported_formats) * BITS_PER_BYTE ||
>         !(supported_formats & BIT(params->format))) {
>         error_report("Stream format is not supported.");
>         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
>     }
>-    if (BIT(params->rate) > sizeof(supported_rates) ||
>+    if (params->rate >= sizeof(supported_rates) * BITS_PER_BYTE ||
>         !(supported_rates & BIT(params->rate))) {
>         error_report("Stream rate is not supported.");
>         return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
>-- 
>2.35.3
>

Thanks for the fix Volker :)

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>