From 7810fe9f2377ea0eebf8d4340e35be5ec1e6dfb6 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 16 Oct 2018 12:59:44 +0200 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/misc/sgi-gru/grukdump.c | 4 ++++ 1 file changed, 4 insertions(+) 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 #include #include + +#include + #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; -- cgit v1.2.3