2021-08-11 11:38:08

by Tuo Li

Subject: [PATCH] gpu: drm: amd: amdgpu: amdgpu_i2c: fix possible uninitialized-variable access in amdgpu_i2c_router_select_ddc_port()

The variable val is declared without initialization, and its address is
passed to amdgpu_i2c_get_byte(). In this function, the value of val is
accessed in:
DRM_DEBUG("i2c 0x%02x 0x%02x read failed\n",
addr, *val);

Also, when amdgpu_i2c_get_byte() returns, val may remain uninitialized,
but it is accessed in:
val &= ~amdgpu_connector->router.ddc_mux_control_pin;

To fix this possible uninitialized-variable access, initialize val to 0 in
amdgpu_i2c_router_select_ddc_port().

Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Tuo Li <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
index bca4dddd5a15..82608df43396 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
@@ -339,7 +339,7 @@ static void amdgpu_i2c_put_byte(struct amdgpu_i2c_chan *i2c_bus,
void
amdgpu_i2c_router_select_ddc_port(const struct amdgpu_connector *amdgpu_connector)
{
- u8 val;
+ u8 val = 0;

if (!amdgpu_connector->router.ddc_valid)
return;
--
2.25.1

2021-08-11 20:18:21

by Alex Deucher

Subject: Re: [PATCH] gpu: drm: amd: amdgpu: amdgpu_i2c: fix possible uninitialized-variable access in amdgpu_i2c_router_select_ddc_port()

Applied. Thanks!

Alex

On Wed, Aug 11, 2021 at 7:35 AM Tuo Li <[email protected]> wrote:
>
> The variable val is declared without initialization, and its address is
> passed to amdgpu_i2c_get_byte(). In this function, the value of val is
> accessed in:
> DRM_DEBUG("i2c 0x%02x 0x%02x read failed\n",
> addr, *val);
>
> Also, when amdgpu_i2c_get_byte() returns, val may remain uninitialized,
> but it is accessed in:
> val &= ~amdgpu_connector->router.ddc_mux_control_pin;
>
> To fix this possible uninitialized-variable access, initialize val to 0 in
> amdgpu_i2c_router_select_ddc_port().
>
> Reported-by: TOTE Robot <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
> index bca4dddd5a15..82608df43396 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_i2c.c
> @@ -339,7 +339,7 @@ static void amdgpu_i2c_put_byte(struct amdgpu_i2c_chan *i2c_bus,
> void
> amdgpu_i2c_router_select_ddc_port(const struct amdgpu_connector *amdgpu_connector)
> {
> - u8 val;
> + u8 val = 0;
>
> if (!amdgpu_connector->router.ddc_valid)
> return;
> --
> 2.25.1
>