[PATCH 3.14 05/43] PCI/AER: Avoid info leak in __print_tlp_header()

Greg Kroah-Hartman
2015-04-17T14:18:39Z

From: Rasmus Villemoes <linux@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@rasmusvillemoes.dk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pci/pcie/aer/aerdrv_errprint.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

--- 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,