Commit 5014aa93 authored Mar 11, 2019 by Pablo Neira Ayuso Committed by Greg Kroah-Hartman May 16, 2019

netfilter: nf_tables: use-after-free in dynamic operations



[ Upstream commit 3f3a390dbd59d236f62cff8e8b20355ef7069e3d ]

Smatch reports:

       net/netfilter/nf_tables_api.c:2167 nf_tables_expr_destroy()
        error: dereferencing freed memory 'expr->ops'

net/netfilter/nf_tables_api.c
    2162 static void nf_tables_expr_destroy(const struct nft_ctx *ctx,
    2163                                   struct nft_expr *expr)
    2164 {
    2165        if (expr->ops->destroy)
    2166                expr->ops->destroy(ctx, expr);
                                                ^^^^
--> 2167        module_put(expr->ops->type->owner);
                           ^^^^^^^^^
    2168 }

Smatch says there are three functions which free expr->ops.

Fixes: b8e204006340 ("netfilter: nft_compat: use .release_ops and remove list of extension")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>

parent 9965da06

net/netfilter/nf_tables_api.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -2113,9 +2113,11 @@ static int nf_tables_newexpr(const struct nft_ctx *ctx,
		static void nf_tables_expr_destroy(const struct nft_ctx *ctx,
		struct nft_expr *expr)
		{
		const struct nft_expr_type *type = expr->ops->type;

		if (expr->ops->destroy)
		expr->ops->destroy(ctx, expr);
		module_put(expr->ops->type->owner);
		module_put(type->owner);
		}

		struct nft_expr nft_expr_init(const struct nft_ctx ctx,