4.19-stable review patch. If anyone has any objections, please let me know.
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[ 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 4c016b49fe2b..06ed55cef962 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2432,7 +2432,7 @@ 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;
lockdep_assert_held(&ctx->net->nft.commit_mutex); /* @@ -2441,8 +2441,9 @@ 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 ad2fe6a7e47d..29d6fc73caf9 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -501,6 +501,7 @@ __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; @@ -511,7 +512,7 @@ __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