[bug report] new kvmalloc() WARN() triggered by DRM ioctls tracking

[Steven Price]

On 16/12/2021 14:15, Boris Brezillon wrote:
> Hi Steve,
> 
> On Thu, 16 Dec 2021 14:02:25 +0000
> Steven Price <steven.price at arm.com> wrote:
> 
>> + Boris
>>
>> On 16/12/2021 12:08, Dan Carpenter wrote:
>>> Hi DRM Devs,
>>>
>>> In commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
>>> from July, Linus added a WARN_ONCE() for "crazy" allocations over 2GB.
>>> I have a static checker warning for this and most of the warnings are
>>> from DRM ioctls.
>>>
>>> drivers/gpu/drm/lima/lima_drv.c:124 lima_ioctl_gem_submit() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/radeon/radeon_cs.c:291 radeon_cs_parser_init() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/v3d/v3d_gem.c:311 v3d_lookup_bos() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/v3d/v3d_gem.c:319 v3d_lookup_bos() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/v3d/v3d_gem.c:601 v3d_get_multisync_post_deps() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c:476 etnaviv_ioctl_gem_submit() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c:477 etnaviv_ioctl_gem_submit() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c:478 etnaviv_ioctl_gem_submit() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c:479 etnaviv_ioctl_gem_submit() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/virtio/virtgpu_ioctl.c:186 virtio_gpu_execbuffer_ioctl() warn: uncapped user size for kvmalloc() will WARN
>>> drivers/gpu/drm/panfrost/panfrost_drv.c:198 panfrost_copy_in_sync() warn: uncapped user size for kvmalloc() will WARN  
>>
>> I believe this one in Panfrost would be fixed by Boris's series
>> reworking the submit ioctl[1].
>>
>> Boris: are you planning on submitting that series soon - or is it worth
>> cherry picking the rework in patch 5 to fix this issue?
> 
> Don't know when I'll get back to it, so I'd recommend cherry-picking
> what you need.

Thanks, no problem - it was mostly when I looked at the code I had the
feeling that "surely this has already been fixed", then discovered your
series was never merged ;)

I'll hammer out a patch for this one issue.

Thanks,

Steve