[PATCH v4 1/2] PCI/AER: Fix memory leak in aer_recover_queue() on kfifo buffer overflow

When ACPI APEI/GHES processes PCIe AER error records, it allocates memory
for aer_capability_regs (aer_regs) from ghes_estatus_pool and passes it
to aer_recover_queue() to be enqueued into aer_recover_ring.

If kfifo_in_spinlocked() fails due to a buffer overflow,
aer_recover_queue() logged an error message but returned without freeing
aer_regs. Because the entry was rejected and never inserted into the
queue, aer_recover_work_func() could never dequeue or free it, leaking
the allocated ghes_estatus_pool memory.

aer_recover_queue() returns void, so the caller ghes_handle_aer() cannot
free the buffer itself: ownership is transferred to the AER code, which
until now only released it on the success path.

Free aer_regs via ghes_estatus_pool_region_free() when
kfifo_in_spinlocked() fails on buffer overflow.

Fixes: e2abc47a5a1a ("ACPI: APEI: Fix AER info corruption when error status data has multiple sections")
Cc: stable@vger.kernel.org
Signed-off-by: Priyank Rathod <redacted>
---
 drivers/pci/pcie/aer.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index d8dcd238fda1..b013b853b555 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c

@@ -1415,11 +1415,14 @@ void aer_recover_queue(int domain, unsigned int bus, unsigned int devfn,
 	};
 
 	if (kfifo_in_spinlocked(&aer_recover_ring, &entry, 1,
-				 &aer_recover_ring_lock))
+				 &aer_recover_ring_lock)) {
 		schedule_work(&aer_recover_work);
-	else
+	} else {
 		pr_err("buffer overflow in recovery for %04x:%02x:%02x.%x\n",
 		       domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
+		ghes_estatus_pool_region_free((unsigned long)aer_regs,
+					      sizeof(struct aer_capability_regs));
+	}
 }
 EXPORT_SYMBOL_GPL(aer_recover_queue);
 #endif

-- 
2.55.0.1082.g2b9226bbc0-goog