rpci: Use pci_dev struct pointer to avoid API breaks

The pci_dev structure is never meant to be used as is, but always as a
pointer. By using the struct itself in undo_pci_write_data, we are risking
data corruption, or buffer overflows if the structure size changes.

This is especially apparent on my system where flashrom segfaults
because I compile it with pciutils 3.3.0 and I run it on a system
with pciutils 3.5.2. The struture size is different and causes a
struct with the wrong size to be sent to the library, with invalid
internal field values.

This has been discovered and discussed in Change ID 18925 [1]

[1] https://review.coreboot.org/#/c/18925/

Change-Id: Icde2e587992ba964d4ff92c33aa659850ba06298
Signed-off-by: Youness Alaoui <kakaroto@kakaroto.homelinux.net>
Reviewed-on: https://review.coreboot.org/20784
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/programmer.h b/programmer.h
index ec00bd9a9..e58fd3257 100644
--- a/programmer.h
+++ b/programmer.h
@@ -195,6 +195,11 @@ uintptr_t pcidev_readbar(struct pci_dev *dev, int bar);
 struct pci_dev *pcidev_init(const struct dev_entry *devs, int bar);
 /* rpci_write_* are reversible writes. The original PCI config space register
  * contents will be restored on shutdown.
+ * To clone the pci_dev instances internally, the `pacc` global
+ * variable has to reference a pci_access method that is compatible
+ * with the given pci_dev handle. The referenced pci_access (not
+ * the variable) has to stay valid until the shutdown handlers are
+ * finished.
  */
 int rpci_write_byte(struct pci_dev *dev, int reg, uint8_t data);
 int rpci_write_word(struct pci_dev *dev, int reg, uint16_t data);