mm/zpool: use prefixed module loading

To avoid potential format string expansion via module parameters, do not
use the zpool type directly in request_module() without a format string.
Additionally, to avoid arbitrary modules being loaded via zpool API
(e.g.  via the zswap_zpool_type module parameter) add a "zpool-" prefix
to the requested module, as well as module aliases for the existing
zpool types (zbud and zsmalloc).

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Acked-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 3 insertions, 1 deletions

diff --git a/mm/zbud.c b/mm/zbud.c
index a05790b..f26e7fc 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -195,6 +195,7 @@ static struct zpool_driver zbud_zpool_driver = {
 	.total_size =	zbud_zpool_total_size,
 };
 
+MODULE_ALIAS("zpool-zbud");
 #endif /* CONFIG_ZPOOL */
 
 /*****************
diff --git a/mm/zpool.c b/mm/zpool.c
index e40612a..739cdf0 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -150,7 +150,7 @@ struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
 	driver = zpool_get_driver(type);
 
 	if (!driver) {
-		request_module(type);
+		request_module("zpool-%s", type);
 		driver = zpool_get_driver(type);
 	}
 
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 4e2fc83..94f38fa 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -315,6 +315,7 @@ static struct zpool_driver zs_zpool_driver = {
 	.total_size =	zs_zpool_total_size,
 };
 
+MODULE_ALIAS("zpool-zsmalloc");
 #endif /* CONFIG_ZPOOL */
 
 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */