Re: [PATCH v3 0/2] cxl: Fix uninitialized access coordinates

On Wed, Aug 12, 2026 at 04:30:33PM +0800, Guixin Liu wrote:
> Two related fixes for stack access_coordinate arrays that are read before
> anything writes them, both reachable on real topologies and both ending up
> in userspace through the access coordinate sysfs attributes.
> 
> Patch 1 is the v2 cdat fix [1] with one more site covered: the coords array
> in cxl_switch_gather_bandwidth() has the same defect as the three arrays in
> cxl_endpoint_gather_bandwidth().
> 
> Patch 2 is new. cxl_endpoint_get_perf_coordinates() returns 0 for an RCD
> without writing the caller's array at all, so cxl_port_perf_data_calculate()
> combines stack residue with the values parsed from the RCD's CDAT.
> 
> Both were pointed out by the Sashiko review bot on the v2 posting of patch 1.
> The third finding in that review - cxl_coordinates_combine() aliasing its
> output onto an input and leaving a member alone when an input bandwidth is
> zero - is the intended "not reported" behaviour and is not addressed here.
>

Hi Guixin,

Thanks for this, both changes LGTM.

Reviewed-by: Richard Cheng <[email protected]>

Best regards,
Richard Cheng.

> [1] https://lore.kernel.org/linux-cxl/[email protected]/
> 
> v2->v3:
> - also zero initialize coords in cxl_switch_gather_bandwidth(), same defect
>   in the sibling gather path (Sashiko bot)
> - new patch 2: clear the output coordinates on the RCD path of
>   cxl_endpoint_get_perf_coordinates(), which currently returns success
>   without writing them (Sashiko bot)
> - drop "endpoint" from the patch 1 subject, it now covers both gather paths
> 
> v1->v2:
> - rebase onto cxl/next
> - rewrite the commit message to describe the behaviour rather than narrate
>   the code change (Alison Schofield)
> 
> Guixin Liu (2):
>   cxl/cdat: Fix uninitialized stack use in bandwidth gathering
>   cxl/port: Fix uninitialized coordinates reported for RCDs
> 
>  drivers/cxl/core/cdat.c | 8 ++++----
>  drivers/cxl/core/port.c | 4 +++-
>  2 files changed, 7 insertions(+), 5 deletions(-)
> 
> 
> base-commit: 7098e9cd98a05c0c5de2fae0c2465f9d966fdd07
> -- 
> 2.43.7
> 
>