[PATCH v5 05/13] ACPI: extlog: Avoid populating software AER metadata from raw hardware buffer

extlog_print_pcie() casts pcie_err->aer_info straight to struct
aer_capability_regs *. That struct embeds struct pcie_tlp_log, whose
software-only header_len and flit fields sit at offset 84 - inside the
96-byte aer_info buffer - so the cast fills them with raw firmware bytes.
pcie_print_tlp_log() uses both to bound a loop over dw[], and a large
header_len walks past the end of the array.

Copy into a zeroed local struct, and only the part of aer_info that maps
onto it: the leading registers and the four Header Log DWORDs. The rest
stays zero, which covers header_len and flit and keeps the Root Error
registers out of the TLP prefix log, where pcie_print_tlp_log() would print
them as end-to-end prefixes.

Reported-by: [email protected]
Closes: https://lore.kernel.org/linux-cxl/[email protected]/
Fixes: e778ffefa34d ("ACPI: extlog: Trace CPER PCI Express Error Section")
Reviewed-by: Alison Schofield <[email protected]>
Reviewed-by: Shuai Xue <[email protected]>
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Dave Jiang <[email protected]>
---
v5:
- Copy only the registers that match the hardware layout instead of all 96
  bytes plus explicit clears, so the rest falls out zero (Jonathan
  Cameron).
---
 drivers/acpi/acpi_extlog.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index 2451362e696d..feb7c002a713 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -137,7 +137,7 @@ static void extlog_print_pcie(struct cper_sec_pcie *pcie_err,
 			      int severity)
 {
 #ifdef ACPI_APEI_PCIEAER
-	struct aer_capability_regs *aer;
+	struct aer_capability_regs aer_regs = {};
 	struct pci_dev *pdev;
 	unsigned int devfn;
 	unsigned int bus;
@@ -149,7 +149,17 @@ static void extlog_print_pcie(struct cper_sec_pcie *pcie_err,
 		return;
 
 	aer_severity = cper_severity_to_aer(severity);
-	aer = (struct aer_capability_regs *)pcie_err->aer_info;
+
+	/*
+	 * struct pcie_tlp_log is larger than the hardware layout, so only the
+	 * leading registers and the four Header Log DWORDs of aer_info map onto
+	 * the struct. Copy that much and leave the rest zero, which covers the
+	 * software-only header_len and flit.
+	 */
+	memcpy(&aer_regs, pcie_err->aer_info,
+	       offsetof(struct aer_capability_regs, header_log) +
+	       PCIE_STD_NUM_TLP_HEADERLOG * sizeof(u32));
+
 	domain = pcie_err->device_id.segment;
 	bus = pcie_err->device_id.bus;
 	devfn = PCI_DEVFN(pcie_err->device_id.device,
@@ -158,7 +168,7 @@ static void extlog_print_pcie(struct cper_sec_pcie *pcie_err,
 	if (!pdev)
 		return;
 
-	pci_print_aer(pdev, aer_severity, aer);
+	pci_print_aer(pdev, aer_severity, &aer_regs);
 	pci_dev_put(pdev);
 #endif
 }
-- 
2.54.0