Commit 29e38801 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso

netfilter: nf_tables: fix use-after-free when deleting compat expressions

nft_compat ops do not have static storage duration, unlike all other
expressions.

When nf_tables_expr_destroy() returns, expr->ops might have been
free'd already, so we need to store next address before calling
expression destructor.

For same reason, we can't deref match pointer after nft_xt_put().

This can be easily reproduced by adding msleep() before
nft_match_destroy() returns.

Fixes: 0ca743a5 ("netfilter: nf_tables: add compatibility layer for x_tables")
Reported-by: 's avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: 's avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: 's avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 0fbcc5b5
......@@ -2457,7 +2457,7 @@ static int nf_tables_getrule(struct net *net, struct sock *nlsk,
static void nf_tables_rule_destroy(const struct nft_ctx *ctx,
struct nft_rule *rule)
{
struct nft_expr *expr;
struct nft_expr *expr, *next;
/*
* Careful: some expressions might not be initialized in case this
......@@ -2465,8 +2465,9 @@ static void nf_tables_rule_destroy(const struct nft_ctx *ctx,
*/
expr = nft_expr_first(rule);
while (expr != nft_expr_last(rule) && expr->ops) {
next = nft_expr_next(expr);
nf_tables_expr_destroy(ctx, expr);
expr = nft_expr_next(expr);
expr = next;
}
kfree(rule);
}
......
......@@ -520,6 +520,7 @@ __nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,
void *info)
{
struct xt_match *match = expr->ops->data;
struct module *me = match->me;
struct xt_mtdtor_param par;
par.net = ctx->net;
......@@ -530,7 +531,7 @@ __nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,
par.match->destroy(&par);
if (nft_xt_put(container_of(expr->ops, struct nft_xt, ops)))
module_put(match->me);
module_put(me);
}
static void
......
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