[PATCH 6.18 137/212] nf_tables: nft_dynset: fix possible stateful expression memleak in error path

Greg Kroah-Hartman
2026-03-23T14:07:46Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 0548a13b5a145b16e4da0628b5936baf35f51b43 ]

If cloning the second stateful expression in the element via GFP_ATOMIC
fails, then the first stateful expression remains in place without being
released.

unreferenced object (percpu) 0x607b97e9cab8 (size 16):
comm "softirq", pid 0, jiffies 4294931867
hex dump (first 16 bytes on cpu 3):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
backtrace (crc 0):
pcpu_alloc_noprof+0x453/0xd80
nft_counter_clone+0x9c/0x190 [nf_tables]
nft_expr_clone+0x8f/0x1b0 [nf_tables]
nft_dynset_new+0x2cb/0x5f0 [nf_tables]
nft_rhash_update+0x236/0x11c0 [nf_tables]
nft_dynset_eval+0x11f/0x670 [nf_tables]
nft_do_chain+0x253/0x1700 [nf_tables]
nft_do_chain_ipv4+0x18d/0x270 [nf_tables]
nf_hook_slow+0xaa/0x1e0
ip_local_deliver+0x209/0x330

Fixes: 563125a73ac3 ("netfilter: nftables: generalize set extension to support for several expressions")
Reported-by: Gurpreet Shergill <giki.shergill@proton.me>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/nf_tables.h | 2 ++
net/netfilter/nf_tables_api.c | 4 ++--
net/netfilter/nft_dynset.c | 10 +++++++++-
3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index c18cffafc9696..4dc080f7f27c6 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -875,6 +875,8 @@ struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,
u64 timeout, u64 expiration, gfp_t gfp);
int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,
struct nft_expr *expr_array[]);
+void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
+ struct nft_set_elem_expr *elem_expr);
void nft_set_elem_destroy(const struct nft_set *set,
const struct nft_elem_priv *elem_priv,
bool destroy_expr);
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b6a575ec33159..0992869b33b35 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6863,8 +6863,8 @@ static void __nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
}
}

-static void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
- struct nft_set_elem_expr *elem_expr)
+void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
+ struct nft_set_elem_expr *elem_expr)
{
struct nft_expr *expr;
u32 size;
diff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c
index 7807d81296646..9123277be03ce 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -30,18 +30,26 @@ static int nft_dynset_expr_setup(const struct nft_dynset *priv,
const struct nft_set_ext *ext)
{
struct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);
+ struct nft_ctx ctx = {
+ .net = read_pnet(&priv->set->net),
+ .family = priv->set->table->family,
+ };
struct nft_expr *expr;
int i;

for (i = 0; i < priv->num_exprs; i++) {
expr = nft_setelem_expr_at(elem_expr, elem_expr->size);
if (nft_expr_clone(expr, priv->expr_array[i], GFP_ATOMIC) < 0)
- return -1;
+ goto err_out;

elem_expr->size += priv->expr_array[i]->ops->size;
}

return 0;
+err_out:
+ nft_set_elem_expr_destroy(&ctx, elem_expr);
+
+ return -1;
}

struct nft_elem_priv *nft_dynset_new(struct nft_set *set,
--
2.51.0