* [PATCH iproute2 1/3] utils: add hexstring_alloc and print_hexstring helpers
2026-07-23 19:11 [PATCH iproute2 0/3] hexstring truncation fixes Stephen Hemminger
@ 2026-07-23 19:11 ` Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 2/3] ip, tc: print hex attributes with print_hexstring Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 3/3] tc: build ct label strings with hexstring_alloc Stephen Hemminger
2 siblings, 0 replies; 4+ messages in thread
From: Stephen Hemminger @ 2026-07-23 19:11 UTC (permalink / raw)
To: netdev; +Cc: Stephen Hemminger
hexstring_n2a() writes into a caller-supplied buffer and silently
truncates when it is too small: the loop stops once fewer than three
bytes remain and returns the partial string. Callers using a fixed
SPRINT_BUF therefore drop trailing bytes for keys wider than 31 bytes.
Add hexstring_alloc(), which formats into a buffer sized to the input
so the full value is always emitted, and print_hexstring(), a wrapper
that formats and prints a binary attribute in one call with no local
buffer to size. print_hexstring() covers the common
print_string(..., hexstring_n2a(...)) pattern.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
include/json_print.h | 3 +++
include/utils.h | 1 +
lib/json_print.c | 12 ++++++++++++
lib/utils.c | 21 +++++++++++++++++++++
4 files changed, 37 insertions(+)
diff --git a/include/json_print.h b/include/json_print.h
index c0d6315f..6a458189 100644
--- a/include/json_print.h
+++ b/include/json_print.h
@@ -84,6 +84,9 @@ _PRINT_FUNC(float, double)
_PRINT_FUNC(tv, const struct timeval *)
#undef _PRINT_FUNC
+void print_hexstring(const char *key, const char *fmt,
+ const __u8 *data, unsigned int len);
+
#define _PRINT_NAME_VALUE_FUNC(type_name, type, format_char) \
void print_##type_name##_name_value(const char *name, type value) \
diff --git a/include/utils.h b/include/utils.h
index f0d45bad..6a8872bf 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -162,6 +162,7 @@ int get_size64(__u64 *size, const char *str);
int hex2mem(const char *buf, uint8_t *mem, int count);
char *hexstring_n2a(const __u8 *str, int len, char *buf, int blen);
+char *hexstring_alloc(const __u8 *str, unsigned int len);
__u8 *hexstring_a2n(const char *str, __u8 *buf, int blen, unsigned int *len);
#define ADDR64_BUF_SIZE sizeof("xxxx:xxxx:xxxx:xxxx")
int addr64_n2a(__u64 addr, char *buff, size_t len);
diff --git a/lib/json_print.c b/lib/json_print.c
index 810d496e..21589073 100644
--- a/lib/json_print.c
+++ b/lib/json_print.c
@@ -179,6 +179,18 @@ int print_color_string(enum output_type type,
return ret;
}
+/* Print binary data as a hex string. The buffer is sized to the input,
+ * so keys of any length are printed in full rather than truncated.
+ */
+void print_hexstring(const char *key, const char *fmt,
+ const __u8 *data, unsigned int len)
+{
+ char *hex = hexstring_alloc(data, len);
+
+ print_string(PRINT_ANY, key, fmt, hex ? : "");
+ free(hex);
+}
+
/*
* value's type is bool. When using this function in FP context you can't pass
* a value to it, you will need to use "is_json_context()" to have different
diff --git a/lib/utils.c b/lib/utils.c
index 50602e59..7a1d8b48 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -1186,6 +1186,27 @@ char *hexstring_n2a(const __u8 *str, int len, char *buf, int blen)
return buf;
}
+/* Format binary as hex into a freshly allocated string; caller frees.
+ * Unlike hexstring_n2a() the result is always sized to hold the full
+ * input, so there is no silent truncation. Returns NULL on allocation
+ * failure.
+ */
+char *hexstring_alloc(const __u8 *str, unsigned int len)
+{
+ char *buf, *ptr;
+ unsigned int i;
+
+ buf = malloc(2 * len + 1);
+ if (!buf)
+ return NULL;
+
+ for (i = 0, ptr = buf; i < len; i++, ptr += 2)
+ sprintf(ptr, "%02x", str[i]);
+ *ptr = '\0';
+
+ return buf;
+}
+
__u8 *hexstring_a2n(const char *str, __u8 *buf, int blen, unsigned int *len)
{
unsigned int cnt = 0;
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH iproute2 2/3] ip, tc: print hex attributes with print_hexstring
2026-07-23 19:11 [PATCH iproute2 0/3] hexstring truncation fixes Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 1/3] utils: add hexstring_alloc and print_hexstring helpers Stephen Hemminger
@ 2026-07-23 19:11 ` Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 3/3] tc: build ct label strings with hexstring_alloc Stephen Hemminger
2 siblings, 0 replies; 4+ messages in thread
From: Stephen Hemminger @ 2026-07-23 19:11 UTC (permalink / raw)
To: netdev; +Cc: Stephen Hemminger
Convert the callers that dump a binary attribute straight to output
over to print_hexstring(). This drops the per-site scratch buffer and,
for phys_port_id and phys_switch_id, fixes truncation of keys wider
than 31 bytes: a 32-byte netdevsim switch id previously printed only
62 of its 64 hex characters because it did not fit SPRINT_BUF.
No change to output for keys that already fit.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
ip/ipaddress.c | 19 ++++++-------------
ip/ipmacsec.c | 7 ++-----
lib/bpf_legacy.c | 6 ++----
tc/f_bpf.c | 8 +++-----
tc/m_action.c | 9 +++------
tc/m_bpf.c | 9 +++------
6 files changed, 19 insertions(+), 39 deletions(-)
diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 6017bc83..7e4cb77c 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -1263,22 +1263,15 @@ int print_linkinfo(struct nlmsghdr *n, void *arg)
rta_getattr_str(tb[IFLA_PHYS_PORT_NAME]));
if (tb[IFLA_PHYS_PORT_ID]) {
- print_string(PRINT_ANY,
- "phys_port_id",
- "portid %s ",
- hexstring_n2a(
- RTA_DATA(tb[IFLA_PHYS_PORT_ID]),
- RTA_PAYLOAD(tb[IFLA_PHYS_PORT_ID]),
- b1, sizeof(b1)));
+ print_hexstring("phys_port_id", "portid %s ",
+ RTA_DATA(tb[IFLA_PHYS_PORT_ID]),
+ RTA_PAYLOAD(tb[IFLA_PHYS_PORT_ID]));
}
if (tb[IFLA_PHYS_SWITCH_ID]) {
- print_string(PRINT_ANY,
- "phys_switch_id",
- "switchid %s ",
- hexstring_n2a(RTA_DATA(tb[IFLA_PHYS_SWITCH_ID]),
- RTA_PAYLOAD(tb[IFLA_PHYS_SWITCH_ID]),
- b1, sizeof(b1)));
+ print_hexstring("phys_switch_id", "switchid %s ",
+ RTA_DATA(tb[IFLA_PHYS_SWITCH_ID]),
+ RTA_PAYLOAD(tb[IFLA_PHYS_SWITCH_ID]));
}
if (tb[IFLA_PARENT_DEV_BUS_NAME]) {
diff --git a/ip/ipmacsec.c b/ip/ipmacsec.c
index fc4c8631..1864ffd3 100644
--- a/ip/ipmacsec.c
+++ b/ip/ipmacsec.c
@@ -661,11 +661,8 @@ static void print_flag(struct rtattr *attrs[], const char *desc,
static void print_key(struct rtattr *key)
{
- SPRINT_BUF(keyid);
-
- print_string(PRINT_ANY, "key", " key %s\n",
- hexstring_n2a(RTA_DATA(key), RTA_PAYLOAD(key),
- keyid, sizeof(keyid)));
+ print_hexstring("key", " key %s\n",
+ RTA_DATA(key), RTA_PAYLOAD(key));
}
#define CIPHER_NAME_GCM_AES_128 "GCM-AES-128"
diff --git a/lib/bpf_legacy.c b/lib/bpf_legacy.c
index 50ca82c1..9d5fcf5f 100644
--- a/lib/bpf_legacy.c
+++ b/lib/bpf_legacy.c
@@ -176,7 +176,6 @@ int bpf_dump_prog_info(FILE *f, uint32_t id)
struct bpf_prog_info info = {};
uint32_t len = sizeof(info);
int fd, ret, dump_ok = 0;
- SPRINT_BUF(tmp);
open_json_object("prog");
print_uint(PRINT_ANY, "id", "id %u ", id);
@@ -190,9 +189,8 @@ int bpf_dump_prog_info(FILE *f, uint32_t id)
int jited = !!info.jited_prog_len;
print_string(PRINT_ANY, "name", "name %s ", info.name);
- print_string(PRINT_ANY, "tag", "tag %s ",
- hexstring_n2a(info.tag, sizeof(info.tag),
- tmp, sizeof(tmp)));
+ print_hexstring("tag", "tag %s ",
+ info.tag, sizeof(info.tag));
print_uint(PRINT_JSON, "jited", NULL, jited);
if (jited && !is_json_context())
fprintf(f, "jited ");
diff --git a/tc/f_bpf.c b/tc/f_bpf.c
index 6dd75445..50fe01ca 100644
--- a/tc/f_bpf.c
+++ b/tc/f_bpf.c
@@ -241,11 +241,9 @@ static int bpf_print_opt(const struct filter_util *qu, FILE *f,
if (tb[TCA_BPF_ID])
dump_ok = bpf_dump_prog_info(f, rta_getattr_u32(tb[TCA_BPF_ID]));
if (!dump_ok && tb[TCA_BPF_TAG]) {
- SPRINT_BUF(b);
-
- print_string(PRINT_ANY, "tag", "tag %s ",
- hexstring_n2a(RTA_DATA(tb[TCA_BPF_TAG]),
- RTA_PAYLOAD(tb[TCA_BPF_TAG]), b, sizeof(b)));
+ print_hexstring("tag", "tag %s ",
+ RTA_DATA(tb[TCA_BPF_TAG]),
+ RTA_PAYLOAD(tb[TCA_BPF_TAG]));
}
if (tb[TCA_BPF_POLICE]) {
diff --git a/tc/m_action.c b/tc/m_action.c
index 6f79fdae..bbc8e6a6 100644
--- a/tc/m_action.c
+++ b/tc/m_action.c
@@ -401,12 +401,9 @@ static int tc_print_one_action(FILE *f, struct rtattr *arg, bool bind)
print_nl();
}
if (tb[TCA_ACT_COOKIE]) {
- int strsz = RTA_PAYLOAD(tb[TCA_ACT_COOKIE]);
- char b1[strsz * 2 + 1];
-
- print_string(PRINT_ANY, "cookie", "\tcookie %s",
- hexstring_n2a(RTA_DATA(tb[TCA_ACT_COOKIE]),
- strsz, b1, sizeof(b1)));
+ print_hexstring("cookie", "\tcookie %s",
+ RTA_DATA(tb[TCA_ACT_COOKIE]),
+ RTA_PAYLOAD(tb[TCA_ACT_COOKIE]));
print_nl();
}
if (tb[TCA_ACT_FLAGS] || tb[TCA_ACT_IN_HW_COUNT]) {
diff --git a/tc/m_bpf.c b/tc/m_bpf.c
index a5de7da1..83b21b57 100644
--- a/tc/m_bpf.c
+++ b/tc/m_bpf.c
@@ -183,12 +183,9 @@ static int bpf_print_opt(const struct action_util *au, FILE *f, struct rtattr *a
d_ok = bpf_dump_prog_info(f,
rta_getattr_u32(tb[TCA_ACT_BPF_ID]));
if (!d_ok && tb[TCA_ACT_BPF_TAG]) {
- SPRINT_BUF(b);
-
- print_string(PRINT_ANY, "tag", "tag %s ",
- hexstring_n2a(RTA_DATA(tb[TCA_ACT_BPF_TAG]),
- RTA_PAYLOAD(tb[TCA_ACT_BPF_TAG]),
- b, sizeof(b)));
+ print_hexstring("tag", "tag %s ",
+ RTA_DATA(tb[TCA_ACT_BPF_TAG]),
+ RTA_PAYLOAD(tb[TCA_ACT_BPF_TAG]));
}
print_action_control("default-action ", parm->action, _SL_);
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH iproute2 3/3] tc: build ct label strings with hexstring_alloc
2026-07-23 19:11 [PATCH iproute2 0/3] hexstring truncation fixes Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 1/3] utils: add hexstring_alloc and print_hexstring helpers Stephen Hemminger
2026-07-23 19:11 ` [PATCH iproute2 2/3] ip, tc: print hex attributes with print_hexstring Stephen Hemminger
@ 2026-07-23 19:11 ` Stephen Hemminger
2 siblings, 0 replies; 4+ messages in thread
From: Stephen Hemminger @ 2026-07-23 19:11 UTC (permalink / raw)
To: netdev; +Cc: Stephen Hemminger
flower_print_ct_label() and ct_print_labels() formatted the key and
optional mask into a fixed on-stack buffer with manual pointer
arithmetic, relying on hexstring_n2a() not to overrun it. Build the
"key/mask" string with hexstring_alloc() and asprintf() instead, which
sizes to the data and drops the open-coded offset handling.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
tc/f_flower.c | 25 ++++++++++++++-----------
tc/m_ct.c | 24 ++++++++++++++----------
2 files changed, 28 insertions(+), 21 deletions(-)
diff --git a/tc/f_flower.c b/tc/f_flower.c
index 6fc2c6a1..d6844282 100644
--- a/tc/f_flower.c
+++ b/tc/f_flower.c
@@ -2619,18 +2619,15 @@ static void flower_print_ct_label(struct rtattr *attr,
{
const unsigned char *str;
bool print_mask = false;
+ char *key, *out;
int data_len, i;
- char out[128];
- char *p;
if (!attr)
return;
data_len = RTA_PAYLOAD(attr);
- hexstring_n2a(RTA_DATA(attr), data_len, out, sizeof(out));
- p = out + data_len*2;
+ key = hexstring_alloc(RTA_DATA(attr), data_len);
- data_len = RTA_PAYLOAD(attr);
str = RTA_DATA(mask_attr);
if (data_len != 16)
print_mask = true;
@@ -2638,16 +2635,22 @@ static void flower_print_ct_label(struct rtattr *attr,
if (str[i] != 0xff)
print_mask = true;
}
+
if (print_mask) {
- *p++ = '/';
- hexstring_n2a(RTA_DATA(mask_attr), data_len, p,
- sizeof(out)-(p-out));
- p += data_len*2;
+ char *mask = hexstring_alloc(RTA_DATA(mask_attr), data_len);
+
+ if (asprintf(&out, "%s/%s", key, mask) < 0)
+ out = NULL;
+ free(mask);
+ free(key);
+ } else {
+ out = key;
}
- *p = '\0';
print_nl();
- print_string(PRINT_ANY, "ct_label", " ct_label %s", out);
+ print_string(PRINT_ANY, "ct_label", " ct_label %s", out ? : "");
+
+ free(out);
}
static void flower_print_ct_zone(struct rtattr *attr,
diff --git a/tc/m_ct.c b/tc/m_ct.c
index e549cb9c..e5eebbda 100644
--- a/tc/m_ct.c
+++ b/tc/m_ct.c
@@ -443,17 +443,15 @@ static void ct_print_labels(struct rtattr *attr,
{
const unsigned char *str;
bool print_mask = false;
- char out[256], *p;
+ char *key, *out;
int data_len, i;
if (!attr)
return;
data_len = RTA_PAYLOAD(attr);
- hexstring_n2a(RTA_DATA(attr), data_len, out, sizeof(out));
- p = out + data_len*2;
+ key = hexstring_alloc(RTA_DATA(attr), data_len);
- data_len = RTA_PAYLOAD(attr);
str = RTA_DATA(mask_attr);
if (data_len != 16)
print_mask = true;
@@ -461,15 +459,21 @@ static void ct_print_labels(struct rtattr *attr,
if (str[i] != 0xff)
print_mask = true;
}
+
if (print_mask) {
- *p++ = '/';
- hexstring_n2a(RTA_DATA(mask_attr), data_len, p,
- sizeof(out)-(p-out));
- p += data_len*2;
+ char *mask = hexstring_alloc(RTA_DATA(mask_attr), data_len);
+
+ if (asprintf(&out, "%s/%s", key, mask) < 0)
+ out = NULL;
+ free(mask);
+ free(key);
+ } else {
+ out = key;
}
- *p = '\0';
- print_string(PRINT_ANY, "label", " label %s", out);
+ print_string(PRINT_ANY, "label", " label %s", out ? : "");
+
+ free(out);
}
static void ct_print_helper(struct rtattr *family, struct rtattr *proto, struct rtattr *name)
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread