[PATCH AUTOSEL 6.1 20/29] nvme: prevent potential spectre v1 gadget

[Sasha Levin]

From: Nitesh Shetty <nj.shetty at samsung.com>

[ Upstream commit 20dc66f2d76b4a410df14e4675e373b718babc34 ]

This patch fixes the smatch warning, "nvmet_ns_ana_grpid_store() warn:
potential spectre issue 'nvmet_ana_group_enabled' [w] (local cap)"
Prevent the contents of kernel memory from being leaked to  user space
via speculative execution by using array_index_nospec.

Signed-off-by: Nitesh Shetty <nj.shetty at samsung.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Sagi Grimberg <sagi at grimberg.me>
Signed-off-by: Keith Busch <kbusch at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/nvme/target/configfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 6a2816f3b4e80..73ae16059a1cb 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -16,6 +16,7 @@
 #endif
 #include <crypto/hash.h>
 #include <crypto/kpp.h>
+#include <linux/nospec.h>
 
 #include "nvmet.h"
 
@@ -508,6 +509,7 @@ static ssize_t nvmet_ns_ana_grpid_store(struct config_item *item,
 
 	down_write(&nvmet_ana_sem);
 	oldgrpid = ns->anagrpid;
+	newgrpid = array_index_nospec(newgrpid, NVMET_MAX_ANAGRPS);
 	nvmet_ana_group_enabled[newgrpid]++;
 	ns->anagrpid = newgrpid;
 	nvmet_ana_group_enabled[oldgrpid]--;
@@ -1580,6 +1582,7 @@ static struct config_group *nvmet_ana_groups_make_group(
 	grp->grpid = grpid;
 
 	down_write(&nvmet_ana_sem);
+	grpid = array_index_nospec(grpid, NVMET_MAX_ANAGRPS);
 	nvmet_ana_group_enabled[grpid]++;
 	up_write(&nvmet_ana_sem);
 
-- 
2.42.0