[PATCH] drm/amdgpu: Handle null atom context in VBIOS info ioctl

[Russell, Kent]

[AMD Official Use Only - General]

Sorry, meant to keep the JIRA part internal. As it stands, the amd/ folder alone has 458 {0}s (plus 55 {}s), and 741 memset-to-0s. So I guess it’s a matter of whether or not we’ll start enforcing memsets vs {0} in the near future. If we intend to switch over soon anyways, we may as well start using memset now and in all future patches.

Kent

From: Francis, David <David.Francis at amd.com>
Sent: Tuesday, September 5, 2023 11:38 AM
To: Russell, Kent <Kent.Russell at amd.com>; amd-gfx at lists.freedesktop.org
Subject: Re: [PATCH] drm/amdgpu: Handle null atom context in VBIOS info ioctl


[AMD Official Use Only - General]


[AMD Official Use Only - General]



Yeah we've had JIRAs (e.g. https://ontrack-internal.amd.com/browse/SWDEV-409711 ) raised that ASAN can't compile the thunk due to using = {0} . Using memset is definitely preferred to save trouble later.



 Kent

This is kernel code, not thunk. {} and {0} are extensively used throughout

the kernel in general and our driver in particular, so I don't see this causing problems.



 David

-----Original Message-----

From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org><mailto:amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Alex

Deucher

Sent: Tuesday, September 5, 2023 10:53 AM

To: Francis, David <David.Francis at amd.com><mailto:David.Francis at amd.com>

Cc: amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org>

Subject: Re: [PATCH] drm/amdgpu: Handle null atom context in VBIOS info ioctl



On Tue, Sep 5, 2023 at 10:50 AM David Francis <David.Francis at amd.com><mailto:David.Francis at amd.com> wrote:

On some APU systems, there is no atom context and so the

atom_context struct is null.



Add a check to the VBIOS_INFO branch of amdgpu_info_ioctl

to handle this case, returning all zeroes.



Signed-off-by: David Francis <David.Francis at amd.com><mailto:David.Francis at amd.com>

---

 drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 19 ++++++++++++-------

 1 file changed, 12 insertions(+), 7 deletions(-)



diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

index 3a48bec10aea..86748290ead7 100644

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

@@ -947,16 +947,21 @@ int amdgpu_info_ioctl(struct drm_device *dev, void

*data, struct drm_file *filp)

                                        ? -EFAULT : 0;

                }

                case AMDGPU_INFO_VBIOS_INFO: {

-                       struct drm_amdgpu_info_vbios vbios_info = {};

+                       struct drm_amdgpu_info_vbios vbios_info = {0};

IIRC, these should be equivalent.  That said, I believe memset is

generally preferred as not all compilers seem to handle these cases

correctly.



Alex



                        struct atom_context *atom_context;



                        atom_context = adev->mode_info.atom_context;

-                       memcpy(vbios_info.name, atom_context->name,

sizeof(atom_context->name));

-                       memcpy(vbios_info.vbios_pn, atom_context->vbios_pn,

sizeof(atom_context->vbios_pn));

-                       vbios_info.version = atom_context->version;

-                       memcpy(vbios_info.vbios_ver_str, atom_context->vbios_ver_str,

-                                               sizeof(atom_context->vbios_ver_str));

-                       memcpy(vbios_info.date, atom_context->date,

sizeof(atom_context->date));

+                       if (atom_context) {

+                               memcpy(vbios_info.name, atom_context->name,

+                                      sizeof(atom_context->name));

+                               memcpy(vbios_info.vbios_pn, atom_context->vbios_pn,

+                                      sizeof(atom_context->vbios_pn));

+                               vbios_info.version = atom_context->version;

+                               memcpy(vbios_info.vbios_ver_str, atom_context-

vbios_ver_str,

+                                      sizeof(atom_context->vbios_ver_str));

+                               memcpy(vbios_info.date, atom_context->date,

+                                      sizeof(atom_context->date));

+                       }



                        return copy_to_user(out, &vbios_info,

                                                min((size_t)size, sizeof(vbios_info))) ? -EFAULT : 0;

--

2.34.1


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