[PATCH 3.16.y-ckt 013/180] PCI/AER: Avoid info leak in __print_tlp_header()

[Luis Henriques]

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rasmus Villemoes <linux at rasmusvillemoes.dk>

commit a1b7f2f6367944d445c6853035830a35c6343939 upstream.

Commit fab4c256a58b ("PCI/AER: Add a TLP header print helper") introduced
the helper function __print_tlp_header(), but contrary to the intention,
the behaviour did change: Since we're taking the address of the parameter
t, the first 4 or 8 bytes printed will be the value of the pointer t
itself, and the remaining 12 or 8 bytes will be who-knows-what (something
from the stack).

We want to show the values of the four members of the struct
aer_header_log_regs; that can be done without ugly and error-prone casts.
On little-endian this should produce the same output as originally
intended, and since no-one has complained about getting garbage output so
far, I think big-endian should be ok too.

Fixes: fab4c256a58b ("PCI/AER: Add a TLP header print helper")
Signed-off-by: Rasmus Villemoes <linux at rasmusvillemoes.dk>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Acked-by: Borislav Petkov <bp at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/pci/pcie/aer/aerdrv_errprint.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/pcie/aer/aerdrv_errprint.c b/drivers/pci/pcie/aer/aerdrv_errprint.c
index 36ed31b52198..3f893dd8fa89 100644
--- a/drivers/pci/pcie/aer/aerdrv_errprint.c
+++ b/drivers/pci/pcie/aer/aerdrv_errprint.c
@@ -127,16 +127,8 @@ static const char *aer_agent_string[] = {
 static void __print_tlp_header(struct pci_dev *dev,
 			       struct aer_header_log_regs *t)
 {
-	unsigned char *tlp = (unsigned char *)&t;
-
-	dev_err(&dev->dev, "  TLP Header:"
-		" %02x%02x%02x%02x %02x%02x%02x%02x"
-		" %02x%02x%02x%02x %02x%02x%02x%02x\n",
-		*(tlp + 3), *(tlp + 2), *(tlp + 1), *tlp,
-		*(tlp + 7), *(tlp + 6), *(tlp + 5), *(tlp + 4),
-		*(tlp + 11), *(tlp + 10), *(tlp + 9),
-		*(tlp + 8), *(tlp + 15), *(tlp + 14),
-		*(tlp + 13), *(tlp + 12));
+	dev_err(&dev->dev, "  TLP Header: %08x %08x %08x %08x\n",
+		t->dw0, t->dw1, t->dw2, t->dw3);
 }
 
 static void __aer_print_error(struct pci_dev *dev,