[PATCH v5 0/3] PCI/AER: Fix ghes_estatus_pool memory leaks in error handling

[Priyank Rathod <rathodpriyank@google.com>]

When firmware reports PCIe Advanced Error Reporting (AER) events via ACPI
APEI GHES (ghes_handle_aer()), it allocates a snapshot buffer from
ghes_estatus_pool to store the aer_capability_regs registers before
enqueuing the error record into aer_recover_ring.

aer_recover_queue() returns void, so ghes_handle_aer() cannot release that
buffer itself; ownership is handed to the AER code, which until now freed
it only on the fully successful path. If the record cannot be enqueued, or
if a dequeued record cannot be mapped to a pci_dev, the allocation is
silently leaked. Under a sustained error storm this exhausts
ghes_estatus_pool, which then breaks GHES hardware error reporting
system-wide.

This series fixes both leak paths and documents the ownership rule:

Patch 1: aer_recover_queue() when kfifo_in_spinlocked() fails because
         aer_recover_ring (capacity 16) is full. The rejected entry is
         freed immediately via ghes_estatus_pool_region_free().

Patch 2: aer_recover_work_func() when a dequeued entry cannot be mapped to
         an active PCI device (pdev is NULL). The loop is restructured so
         ghes_estatus_pool_region_free() runs unconditionally for every
         dequeued item.

Patch 3: Add a kernel-doc comment stating that aer_recover_queue() takes
         ownership of @aer_regs, which must be allocated from
         ghes_estatus_pool. This is documentation only, so unlike
         patches 1 and 2 it has no Fixes: or Cc: stable tag.

Signed-off-by: Priyank Rathod <rathodpriyank@google.com>
---
Changes in v5:
- Add patch 3, a kernel-doc comment on aer_recover_queue() stating that
  it takes ownership of @aer_regs, which must come from ghes_estatus_pool
  (suggested by Kuppuswamy Sathyanarayanan). It is a separate patch so
  that the two fixes stay minimal for stable backports, and because the
  comment is only accurate once patch 2 is applied.
- Add Kuppuswamy's Reviewed-by to patches 1 and 2. Their code is
  unchanged from v4.
- Still applies cleanly to pci/next (94e8d4e94266), before or after
  Lukas' "Error reporting for AER-incapable devices" series:
  https://lore.kernel.org/r/cover.1790531238.git.lukas@wunner.de
- Cc Kuppuswamy Sathyanarayanan, Jonathan Cameron, Ilpo Järvinen and
  Dave Jiang, plus Shiju Jose and Rafael J. Wysocki as the author and
  committer of the commit in Fixes:.
- Link to v4: https://lore.kernel.org/r/20260918-b4-fix-aer-memleaks-v4-0-f0a2c21ed1d1@google.com

Changes in v4:
- Rebased onto v7.3-rc3+ (f259f446f519); applies cleanly to pci/next as
  well. No conflicts with the Advisory Non-Fatal Error support that landed
  in the meantime.
- Added missing Fixes: e2abc47a5a1a ("ACPI: APEI: Fix AER info corruption
  when error status data has multiple sections") and Cc: stable to both
  patches; that commit (v6.7-rc1) introduced the ghes_estatus_pool
  allocation whose ownership these paths drop.
- Patch 1: use braces on both arms of the if/else and fix the continuation
  alignment (checkpatch --strict).
- Both patches now build warning-free with W=1 and CONFIG_ACPI_APEI_PCIEAER=y
  (earlier revisions were only build-tested with APEI disabled, which
  compiles neither of the modified functions).
- Explained in both commit messages why the caller cannot free the buffer,
  and when the missing-pci_dev path is reachable.
- Cc: Lukas Wunner, who has been active in this code.
- Link to v3: https://lore.kernel.org/r/20260803-b4-fix-aer-memleaks-v3-1-e87159611933@google.com

Changes in v3:
- Resent to fix threading of the series.
- Link to v2: https://lore.kernel.org/r/20260803-b4-fix-aer-memleaks-v2-1-fd199b0171fd@google.com

Changes in v2:
- Refactored aer_recover_work_func() to ensure ghes_estatus_pool_region_free()
  is called unconditionally for every dequeued record.
- Added Patch 1 to fix related memory leak in aer_recover_queue() on kfifo
  buffer overflow.
- Link to v1: https://lore.kernel.org/r/20260803183853.432459-2-rathodpriyank@google.com

---
Priyank Rathod (3):
      PCI/AER: Fix memory leak in aer_recover_queue() on kfifo buffer overflow
      PCI/AER: Fix memory leak in aer_recover_work_func() when pci_dev is missing
      PCI/AER: Document that aer_recover_queue() takes ownership of aer_regs

 drivers/pci/pcie/aer.c | 48 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 13 deletions(-)
---
base-commit: f259f446f5198d98e13756d2cd531812a0ad3064
change-id: 20260803-b4-fix-aer-memleaks-524a1bd5e888

Best regards,
-- 
Priyank Rathod <rathodpriyank@google.com>