Re: [PATCH v7 0/7] cxl: Sashiko bug fixes

[Dave Jiang]

On 9/1/26 10:38 PM, Richard Cheng wrote:
> Seven independent, pre-existing bugs in the CXL core, reported by
> sashiko.
> 
> Patch 1: Get/Set Feature derive each mailbox command's offset from the
> starting offset plus the amount of data already transferred, then store
> it in a 16-bit field. A large offset/count supplied through fwctl can
> cause a later offset to exceed the representable feature extent and be
> truncated by cpu_to_le16(), targeting the wrong feature data. Reject
> invalid ranges up front.
> 
> Change cxl_get_feature() to return ssize_t so invalid input and mailbox
> failures are reported as negative errno instead of being conflated with
> a zero-byte result. Update all EDAC callers for the signed return
> contract while preserving the existing fwctl RPC response behavior.
> 
> Patch 2: cxl_get_poison_unmapped() aborted its whole partition sweep on
> the first fully-mapped partition, silently skipping unmapped poison in
> all later partitions. Skip that partition instead.
> 
> Patch 3: the same function tolerated the -EFAULT a RAM partition returns
> for Get Poison List but left it in rc, so a benign fault on the last
> scanned partition surfaced as a spurious read failure. Clear rc, as
> poison_by_decoder() already does.
> 
> Patch 4: the same function also ignored the ctx->offset handoff from
> poison_by_decoder() and derived its scan start from the highest DPA
> allocation, so the DPA of allocated-but-uncommitted decoders was never
> scanned by either phase. Resume the sweep at ctx->offset.
> 
> Patch 5: cxl_get_poison_by_memdev() overwrote rc on each partition
> query, so an earlier partition's failure was masked by a later success
> and unscanned poison was reported as a clean list. Stop on any error
> not tolerated as a RAM -EFAULT.
> 
> Patch 6: poison_by_decoder() assumed every decoder with a DPA reservation
> was assigned to a partition. Malformed device DPA metadata can leave
> dpa_res set while part remains -1, causing a poison scan to access
> before the partition array. Reject such decoders before the lookup.
> 
> Patch 7: the Get and Set Feature fwctl handlers converted all helper
> failures into normal RPC responses, sometimes with a SUCCESS device
> status. Propagate delivery failures as ioctl errors while continuing to
> report actual device errors through rpc_out->retval.
> 
> A nonzero short Get Feature response is valid when Offset + Count runs
> past the end of the feature. Preserve the returned bytes as a successful
> partial transfer, reject unexpected zero-length success responses, and
> require fixed-format EDAC callers to receive their complete attribute
> structures before consuming them.
> 
> Changes since v6 [1]:
> - Patch 7: Remove redundant braces. (Dave Jiang)
> 
> [1]:
> https://lore.kernel.org/linux-cxl/20260826014508.9989-1-icheng@xxxxxxxxxx/
> 
> 
> Richard Cheng (7):
>   cxl/features: Reject feature offset that overflows 16-bit field
>   cxl/region: Scan all partitions for unmapped poison
>   cxl/region: Don't leak tolerated RAM -EFAULT from unmapped poison scan
>   cxl/region: Start unmapped poison scan at the committed decoder
>     boundary
>   cxl/memdev: Don't overwrite the error from an earlier partition poison
>     query
>   cxl/region: Reject poison scan for decoder without a partition
>   cxl/fwctl: Propagate feature RPC delivery errors
> 
>  drivers/cxl/core/core.h     |  8 +++---
>  drivers/cxl/core/edac.c     | 30 +++++++++++++-------
>  drivers/cxl/core/features.c | 56 ++++++++++++++++++++++++-------------
>  drivers/cxl/core/memdev.c   |  2 ++
>  drivers/cxl/core/region.c   | 15 +++++-----
>  5 files changed, 71 insertions(+), 40 deletions(-)
> 
> 
> base-commit: 7098e9cd98a05c0c5de2fae0c2465f9d966fdd07

Patches 1 and 7 applied to cxl/next
51493ff66ad6
3eb3376944ac