[PATCH] netfilter: x_tables: replace strlcat() with snprintf()
From: Ian Bridges <hidden>
Date: 2026-06-26 22:25:40
Also in:
linux-hardening, lkml, netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
In preparation for removing the deprecated strlcat() API[1], replace the strscpy()/strlcat() pairs in xt_proto_init() and xt_proto_fini() with snprintf(), which builds each /proc file name in a single call. Each name is "<prefix><suffix>", where <prefix> is the address-family string xt_prefix[af] and <suffix> is one of the FORMAT_TABLES, FORMAT_MATCHES or FORMAT_TARGETS literals. snprintf() with a "%s%s" format produces the same NUL-terminated, length-bounded string as the strscpy()/strlcat() chain it replaces, so the proc entry names are unchanged. Link: https://github.com/KSPP/linux/issues/370 [1] Signed-off-by: Ian Bridges <redacted> --- net/netfilter/x_tables.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 4e6708c23922..56f4546be336 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c@@ -2033,8 +2033,7 @@ int xt_proto_init(struct net *net, u_int8_t af) root_uid = make_kuid(net->user_ns, 0); root_gid = make_kgid(net->user_ns, 0); - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_TABLES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_TABLES); proc = proc_create_net_data(buf, 0440, net->proc_net, &xt_table_seq_ops, sizeof(struct seq_net_private), (void *)(unsigned long)af);
@@ -2043,8 +2042,7 @@ int xt_proto_init(struct net *net, u_int8_t af) if (uid_valid(root_uid) && gid_valid(root_gid)) proc_set_user(proc, root_uid, root_gid); - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_MATCHES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_MATCHES); proc = proc_create_seq_private(buf, 0440, net->proc_net, &xt_match_seq_ops, sizeof(struct nf_mttg_trav), (void *)(unsigned long)af);
@@ -2053,8 +2051,7 @@ int xt_proto_init(struct net *net, u_int8_t af) if (uid_valid(root_uid) && gid_valid(root_gid)) proc_set_user(proc, root_uid, root_gid); - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_TARGETS, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_TARGETS); proc = proc_create_seq_private(buf, 0440, net->proc_net, &xt_target_seq_ops, sizeof(struct nf_mttg_trav), (void *)(unsigned long)af);
@@ -2068,13 +2065,11 @@ int xt_proto_init(struct net *net, u_int8_t af) #ifdef CONFIG_PROC_FS out_remove_matches: - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_MATCHES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_MATCHES); remove_proc_entry(buf, net->proc_net); out_remove_tables: - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_TABLES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_TABLES); remove_proc_entry(buf, net->proc_net); out: return -1;
@@ -2087,16 +2082,13 @@ void xt_proto_fini(struct net *net, u_int8_t af) #ifdef CONFIG_PROC_FS char buf[XT_FUNCTION_MAXNAMELEN]; - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_TABLES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_TABLES); remove_proc_entry(buf, net->proc_net); - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_TARGETS, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_TARGETS); remove_proc_entry(buf, net->proc_net); - strscpy(buf, xt_prefix[af], sizeof(buf)); - strlcat(buf, FORMAT_MATCHES, sizeof(buf)); + snprintf(buf, sizeof(buf), "%s%s", xt_prefix[af], FORMAT_MATCHES); remove_proc_entry(buf, net->proc_net); #endif /*CONFIG_PROC_FS*/ }
--
2.47.3