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Message-Id: <20181126105053.014239351@linuxfoundation.org>
Date: Mon, 26 Nov 2018 11:51:22 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH 4.4 67/70] drivers/misc/sgi-gru: fix Spectre v1 vulnerability
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Gustavo A. R. Silva <gustavo@...eddedor.com>
commit fee05f455ceb5c670cbe48e2f9454ebc4a388554 upstream.
req.gid can be 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:
vers/misc/sgi-gru/grukdump.c:200 gru_dump_chiplet_request() warn:
potential spectre issue 'gru_base' [w]
Fix this by sanitizing req.gid before calling macro GID_TO_GRU, which
uses it to index gru_base.
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@...r.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/misc/sgi-gru/grukdump.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/misc/sgi-gru/grukdump.c
+++ b/drivers/misc/sgi-gru/grukdump.c
@@ -27,6 +27,9 @@
#include <linux/delay.h>
#include <linux/bitops.h>
#include <asm/uv/uv_hub.h>
+
+#include <linux/nospec.h>
+
#include "gru.h"
#include "grutables.h"
#include "gruhandles.h"
@@ -196,6 +199,7 @@ int gru_dump_chiplet_request(unsigned lo
/* Currently, only dump by gid is implemented */
if (req.gid >= gru_max_gids)
return -EINVAL;
+ req.gid = array_index_nospec(req.gid, gru_max_gids);
gru = GID_TO_GRU(req.gid);
ubuf = req.buf;
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