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

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: b8e2040063 ("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>
This commit is contained in:
Pablo Neira Ayuso 2019-03-11 13:04:16 +01:00
parent 273fe3f100
commit 3f3a390dbd
1 changed files with 3 additions and 1 deletions
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4
net/netfilter/nf_tables_api.c
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@ -2162,9 +2162,11 @@ 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,