ACK/Cmnt: [PATCH 0/1][SRU][Jammy] Fix AMD Yellow Carp GPU UBSAN warning array-index-out-of-bounds

[Tim Gardner]

Acked-by: Tim Gardner <tim.gardner at canonical.com>

Nominate Jammy in the bug report.

On 1/18/22 12:44 PM, You-Sheng Yang wrote:
> BugLink: https://bugs.launchpad.net/bugs/1958229
> 
> [Impact]
> 
> On HP Lockheed16, following UBSAN warning dumped at boot and the first
> USB4 port is disabled:
> 
>    UBSAN: array-index-out-of-bounds in /drivers/gpu/drm/amd/amdgpu/../display/dc/dcn31/dcn31_resource.c:1295:22
>    index 6 is out of range for type 'dcn10_stream_enc_registers[5]'
> 
> This is a follow-up for bug 1953008 on Jammy, which only happens when
> patches for USB4 alt mode were applied and tested on a HP platform.
> 
> [Fix]
> 
> Commit d374d3b49321 ("drm/amd/display: Fix out of bounds access on DNC31
> stream encoder regs") from Linus' tree.
> 
> [Test Case]
> 
> Apply and check no more such warning, and USB alt mode should work.
> 
> [Where problems could occur]
> 
> No. This specifies the expected array size to avoid UBSAN warning.
> 
> [Other Info]
> 
> While UBSAN is only turned on by default on 5.15 kernels or newer, and
> we didn't find this issue on oem-5.14, so only Jammy is nominated here.
> 
> Nicholas Kazlauskas (1):
>    drm/amd/display: Fix out of bounds access on DNC31 stream encoder regs
> 
>   drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 

-- 
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Tim Gardner
Canonical, Inc