4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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;
