diff options
| author | Florian Westphal <fw@strlen.de> | 2018-11-12 22:43:45 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-11-13 09:57:33 +0100 |
| commit | 29e3880109e357fdc607b4393f8308cef6af9413 (patch) | |
| tree | c1bd28510eb2dbacce9076ca3f4b4eb6c173a515 /net/netfilter | |
| parent | 0fbcc5b568edab7d848b7c7fa66d44ffbd4133c0 (diff) | |
| download | blackbird-op-linux-29e3880109e357fdc607b4393f8308cef6af9413.tar.gz blackbird-op-linux-29e3880109e357fdc607b4393f8308cef6af9413.zip | |
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.c | 5 | ||||
| -rw-r--r-- | 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 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 |
