Re: [PATCH] drm/amdgpu: zero reg_state buffer before filling it

["Christian König" <christian.koenig@amd.com>]

On 9/14/26 15:56, Dmitriy Chumachenko wrote:
> The reg_state readouts return szbuf bytes but never write the pad members
> of the headers and of amdgpu_smn_reg_data (and, for pcie, the fields
> skipped when the upstream port or AER capability is absent). The sysfs
> buffer is a plain kmalloc(), so those bytes leak stale slab data to any
> local user through the 0444 reg_state attribute.
> 
> Zero the buffer once the size is known.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 081a6eda2b25 ("drm/amdgpu: Read aquavanjaram PCIE register state")
> Signed-off-by: Dmitriy Chumachenko <Dmitry.Chumachenko@cyberprotect.ru>

Good catch, but stuff like that should be handled by using kzalloc() instead of calling memset it manually.

Regards,
Christian.

> ---
>  drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> index 72ea37dbfea8..0086de0f685d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> +++ b/drivers/gpu/drm/amd/amdgpu/aqua_vanjaram.c
> @@ -610,6 +610,8 @@ static ssize_t aqua_vanjaram_read_pcie_state(struct amdgpu_device *adev,
>         if (max_size < szbuf)
>                 return -EOVERFLOW;
> 
> +       memset(buf, 0, szbuf);
> +
>         pcie_regs = (struct amdgpu_regs_pcie_v1_0 *)((uint8_t *)buf +
>                                                      sizeof(*pcie_reg_state));
>         pcie_regs->inst_header.instance = 0;
> @@ -702,6 +704,8 @@ static ssize_t aqua_vanjaram_read_xgmi_state(struct amdgpu_device *adev,
>         if (max_size < szbuf)
>                 return -EOVERFLOW;
> 
> +       memset(buf, 0, szbuf);
> +
>         p = &xgmi_reg_state->xgmi_state_regs[0];
>         for_each_inst(i, adev->aid_mask) {
>                 for (j = 0; j < xgmi_inst; ++j) {
> @@ -776,6 +780,8 @@ static ssize_t aqua_vanjaram_read_wafl_state(struct amdgpu_device *adev,
>         if (max_size < szbuf)
>                 return -EOVERFLOW;
> 
> +       memset(buf, 0, szbuf);
> +
>         p = &wafl_reg_state->wafl_state_regs[0];
>         for_each_inst(i, adev->aid_mask) {
>                 for (j = 0; j < wafl_inst; ++j) {
> @@ -902,6 +908,8 @@ static ssize_t aqua_vanjaram_read_usr_state(struct amdgpu_device *adev,
>         if (max_size < szbuf)
>                 return -EOVERFLOW;
> 
> +       memset(buf, 0, szbuf);
> +
>         p = &usr_reg_state->usr_state_regs[0];
>         for_each_inst(i, adev->aid_mask) {
>                 usr_regs = (struct amdgpu_regs_usr_v1_0 *)p;
> --
> 2.49.0
>