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authorFlorian Westphal <fw@strlen.de>2018-11-12 22:43:45 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2018-11-13 09:57:33 +0100
commit29e3880109e357fdc607b4393f8308cef6af9413 (patch)
treec1bd28510eb2dbacce9076ca3f4b4eb6c173a515 /net/netfilter
parent0fbcc5b568edab7d848b7c7fa66d44ffbd4133c0 (diff)
downloadlinux-29e3880109e357fdc607b4393f8308cef6af9413.tar.bz2
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: 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>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_tables_api.c5
-rw-r--r--net/netfilter/nft_compat.c3
2 files changed, 5 insertions, 3 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e496030fdc3b..ddeaa1990e1e 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2457,7 +2457,7 @@ err:
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);
}
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 9d0ede474224..7334e0b80a5e 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -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