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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-10-16 12:59:44 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-11-27 16:08:02 +0100
commitb61865ef9b88adc09188f736b590e54602410ed3 (patch)
parent1b44cb3b63f1b745d6e8e4e382b0131d9d2b480a (diff)
drivers/misc/sgi-gru: fix Spectre v1 vulnerability
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@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/misc/sgi-gru/grukdump.c b/drivers/misc/sgi-gru/grukdump.c
index 313da3150262..1540a7785e14 100644
--- 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 long arg)
/* 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;