[PATCH AUTOSEL 4.14 09/69] netfilter: nf_tables: fix use-after-free when deleting compat expressions
From: Sasha Levin <sashal@kernel.org>
Date: 2018-12-05 09:43:59
Also in:
lkml, netfilter-devel, stable
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Florian Westphal <fw@strlen.de>
[ Upstream commit 29e3880109e357fdc607b4393f8308cef6af9413 ]
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: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_tables_api.c | 5 +++--
net/netfilter/nft_compat.c | 3 ++-
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 3ae365f92bff..ea1e57daf50e 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c@@ -2252,7 +2252,7 @@ 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
@@ -2260,8 +2260,9 @@ 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); }
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 6da1cec1494a..7533c2fd6b76 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c@@ -497,6 +497,7 @@ __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;
@@ -507,7 +508,7 @@ __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
--
2.17.1