| From fee05f455ceb5c670cbe48e2f9454ebc4a388554 Mon Sep 17 00:00:00 2001 |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| Date: Tue, 16 Oct 2018 12:59:44 +0200 |
| Subject: drivers/misc/sgi-gru: fix Spectre v1 vulnerability |
| |
| From: Gustavo A. R. Silva <gustavo@embeddedor.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@vger.kernel.org |
| Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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; |