[PATCH] scsi: mptfusion: Fix potential Spectre v1 vulnerabilities

From: Gustavo A. R. Silva
Date: Fri Dec 14 2018 - 11:47:55 EST

karg.hdr.id and port are indirectly controlled by user-space, hence leading
to a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/message/fusion/mptctl.c:1360 mptctl_getiocinfo() warn: potential spectre issue 'ioc->pfacts' [r]
drivers/message/fusion/mptctl.c:2788 mptctl_hp_targetinfo() warn: potential spectre issue 'hd->sel_timeout' [r] (local cap)

Fix this by sanitizing both karg.hdr.id and port before using them to
index ioc->pfacts and hd->sel_timeout.

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
drivers/message/fusion/mptctl.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/message/fusion/mptctl.c b/drivers/message/fusion/mptctl.c
index 8d22d6134a89..f6c1311ae86f 100644
--- a/drivers/message/fusion/mptctl.c
+++ b/drivers/message/fusion/mptctl.c
@@ -66,6 +66,8 @@
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

+#include <linux/nospec.h>
#define COPYRIGHT "Copyright (c) 1999-2008 LSI Corporation"
#define MODULEAUTHOR "LSI Corporation"
#include "mptbase.h"
@@ -1306,7 +1308,7 @@ mptctl_getiocinfo (unsigned long arg, unsigned int data_size)
return -EINVAL;
- port = karg->hdr.port;
+ port = array_index_nospec(karg->hdr.port, 2);

karg->port = port;
pdev = (struct pci_dev *) ioc->pcidev;
@@ -2689,6 +2691,7 @@ mptctl_hp_targetinfo(unsigned long arg)
if (karg.hdr.id >= MPT_MAX_FC_DEVICES)
return -EINVAL;
+ karg.hdr.id = array_index_nospec(karg.hdr.id, MPT_MAX_FC_DEVICES);
dctlprintk(ioc, printk(MYIOC_s_DEBUG_FMT "mptctl_hp_targetinfo called.\n",