[PATCH v2] mm/zpool: use prefixed module loading

[Kees Cook <keescook@chromium.org>]

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>
---
v2:
- moved module aliases into ifdefs (ddstreet)
---
 mm/zbud.c     | 1 +
 mm/zpool.c    | 2 +-
 mm/zsmalloc.c | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/zbud.c b/mm/zbud.c
index a05790b1915e..f26e7fcc7fa2 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 e40612a1df00..739cdf0d183a 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 4e2fc83cb394..94f38fac5e81 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 */
-- 
1.9.1


-- 
Kees Cook
Chrome OS Security

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