[PATCH v3] pci: Limit VPD length for megaraid_sas adapter

From: Babu Moger
Date: Thu Nov 19 2015 - 13:18:59 EST

Reading or Writing of PCI VPD data causes system panic.
We saw this problem by running "lspci -vvv" in the beginning.
However this can be easily reproduced by running
cat /sys/bus/devices/XX../vpd

VPD length has been set as 32768 by default. Accessing vpd
will trigger read/write of 32k. This causes problem as we
could read data beyond the VPD end tag. Behaviour is un-
predictable when this happens. I see some other adapter doing
similar quirks(commit bffadffd43d4 ("PCI: fix VPD limit quirk
for Broadcom 5708S"))

I see there is an attempt to fix this right way.
https://patchwork.ozlabs.org/patch/534843/ or

Tried to fix it this way, but problem is I dont see the proper
start/end TAGs(at least for this adapter) at all. The data is
mostly junk or zeros. This patch fixes the issue by setting the
vpd length to 0x80.

Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
Reviewed-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx>

Changes since v2 -> v3
Changed the vpd length from 0 to 0x80 which leaves the
option open for someone to read first few bytes.

Changes since v1 -> v2
Removed the changes in pci_id.h. Kept all the vendor
ids in quirks.c
drivers/pci/quirks.c | 38 ++++++++++++++++++++++++++++++++++++++
1 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b03373f..b8774e2 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2123,6 +2123,44 @@ static void quirk_via_cx700_pci_parking_caching(struct pci_dev *dev)
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, 0x324e, quirk_via_cx700_pci_parking_caching);

+ * A read/write to sysfs entry ('/sys/bus/pci/devices/<id>/vpd')
+ * will dump 32k of data. The default length is set as 32768.
+ * Reading a full 32k will cause an access beyond the VPD end tag.
+ * The system behaviour at that point is mostly unpredictable.
+ * Also I dont believe vendors have implemented this VPD headers properly.
+ * Atleast I dont see it in following megaraid sas controller.
+ * That is why adding the quirk here.
+ */
+static void quirk_megaraid_sas_limit_vpd(struct pci_dev *dev)
+ if (dev->vpd)
+ dev->vpd->len = 0x80;
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
+ quirk_megaraid_sas_limit_vpd);
* For Broadcom 5706, 5708, 5709 rev. A nics, any read beyond the
* VPD end tag will hang the device. This problem was initially
* observed when a vpd entry was created in sysfs

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