[PATCH 0/3] lib: remove use of strncpy

[PATCH 0/3] lib: remove use of strncpy

[Bruce Richardson]

Taking a lead from the kernel, which has just finished a multi-year
effort to remove use of strncpy[1], rework DPDK to remove use of the
same function. This series removes all remaining uses of strncpy
in lib directory.

[1] https://www.phoronix.com/news/Linux-7.2-Drops-strncpy

Bruce Richardson (3):
  ethdev: remove use of strncpy
  eventdev: improve bounds checks for names in adapter create
  vhost: remove use of strncpy

 lib/ethdev/ethdev_driver.c              |  7 ++++++-
 lib/eventdev/rte_event_eth_tx_adapter.c |  4 ++--
 lib/vhost/socket.c                      |  4 +---
 lib/vhost/vduse.c                       |  2 +-
 lib/vhost/vhost.c                       | 12 +++---------
 lib/vhost/vhost.h                       |  2 +-
 6 files changed, 14 insertions(+), 17 deletions(-)

--
2.53.0

[PATCH 1/3] ethdev: remove use of strncpy

[Bruce Richardson]

The use of strncpy is not generally recommended, so replace it in code
tokenizing the representor list. Since its use in the function is not
involving null-terminated strings (we know that copied block will
not involve a null value in it), we can replace strncpy with memcpy
rather than a string function. This keeps the original intent of the
code.

For extra safety, also add in an explicit bounds check on the length
value before doing the memcpy.

Fixes: 9a9eb104edf6 ("ethdev: parse multiple representor devargs")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/ethdev/ethdev_driver.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/ethdev/ethdev_driver.c b/lib/ethdev/ethdev_driver.c
index 70ddce5bfc..4043ce898f 100644
--- a/lib/ethdev/ethdev_driver.c
+++ b/lib/ethdev/ethdev_driver.c
@@ -583,10 +583,15 @@ eth_dev_tokenise_representor_list(char *p_val, struct rte_eth_devargs *eth_devar
 		return devargs;
 	}
 
+	/* len - 2 strips the outer '[' and ']'; guard against underflow and overflow */
+	if (len < 2 || (len - 2) >= BUFSIZ) {
+		RTE_ETHDEV_LOG_LINE(ERR, "Representor list too long or malformed: %s", p_val);
+		return -EINVAL;
+	}
 	memset(str, 0, BUFSIZ);
 	memset(da_val, 0, BUFSIZ);
 	/* Remove the exterior [] of the consolidated list */
-	strncpy(str, &p_val[1], len - 2);
+	memcpy(str, &p_val[1], len - 2);
 	while (1) {
 		if (str[i] == '\0') {
 			if (da_val[0] != '\0') {
-- 
2.53.0

[PATCH 2/3] eventdev: improve bounds checks for names in adapter create

[Bruce Richardson]

The bounds checks for snprintf and then strncpy used different constant
defines, which happened to resolve to the same value (32). Make this
code more resilient by using sizeof() operator rather than the defines,
and replace use of strncpy with the better strlcpy.

Fixes: a3bbf2e09756 ("eventdev: add eth Tx adapter implementation")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/eventdev/rte_event_eth_tx_adapter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/eventdev/rte_event_eth_tx_adapter.c b/lib/eventdev/rte_event_eth_tx_adapter.c
index 91c7be55c7..d531da5d69 100644
--- a/lib/eventdev/rte_event_eth_tx_adapter.c
+++ b/lib/eventdev/rte_event_eth_tx_adapter.c
@@ -748,7 +748,7 @@ txa_service_adapter_create_ext(uint8_t id, struct rte_eventdev *dev,
 		return -EINVAL;
 
 	socket_id = dev->data->socket_id;
-	snprintf(mem_name, TXA_MEM_NAME_LEN,
+	snprintf(mem_name, sizeof(mem_name),
 		"rte_event_eth_txa_%d",
 		id);
 
@@ -767,7 +767,7 @@ txa_service_adapter_create_ext(uint8_t id, struct rte_eventdev *dev,
 	txa->id = id;
 	txa->eventdev_id = dev->data->dev_id;
 	txa->socket_id = socket_id;
-	strncpy(txa->mem_name, mem_name, TXA_SERVICE_NAME_LEN);
+	strlcpy(txa->mem_name, mem_name, sizeof(txa->mem_name));
 	txa->conf_cb = conf_cb;
 	txa->conf_arg = conf_arg;
 	txa->service_id = TXA_INVALID_SERVICE_ID;
-- 
2.53.0

[PATCH 3/3] vhost: remove use of strncpy

[Bruce Richardson]

The strlcpy is preferred over use of strncpy, which removes the need to
try and explicitly null-terminate some string buffers. We can also
simplify some name length handling as a result of this, as we no longer
need to use strnlen to clamp the length before calling the set_ifname
function.

Fixes: a277c7159876 ("vhost: refactor code structure")
Fixes: 0adb8eccc6a6 ("vhost: add VDUSE device creation and destruction")
Fixes: c171a2d5ff17 ("vhost: use strlcpy instead of strncpy")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/vhost/socket.c |  4 +---
 lib/vhost/vduse.c  |  2 +-
 lib/vhost/vhost.c  | 12 +++---------
 lib/vhost/vhost.h  |  2 +-
 4 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 70e582a18d..0943b3e9bb 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -207,7 +207,6 @@ static void
 vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 {
 	int vid;
-	size_t size;
 	struct vhost_user_connection *conn;
 	int ret;
 	struct virtio_net *dev;
@@ -226,8 +225,7 @@ vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 		goto err;
 	}
 
-	size = strnlen(vsocket->path, PATH_MAX);
-	vhost_set_ifname(vid, vsocket->path, size);
+	vhost_set_ifname(vid, vsocket->path);
 
 	vhost_setup_virtio_net(vid, vsocket->use_builtin_virtio_net,
 		vsocket->net_compliant_ol_flags, vsocket->stats_enabled,
diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
index 0b5d158fee..f8a4a8edcb 100644
--- a/lib/vhost/vduse.c
+++ b/lib/vhost/vduse.c
@@ -796,7 +796,7 @@ vduse_device_create(const char *path, bool compliant_ol_flags, bool extbuf, bool
 		goto out_dev_destroy;
 	}
 
-	strncpy(dev->ifname, path, IF_NAME_SZ - 1);
+	strlcpy(dev->ifname, path, sizeof(dev->ifname));
 	dev->vduse_ctrl_fd = control_fd;
 	dev->vduse_dev_fd = dev_fd;
 
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 7e68b2c3be..fde8acb00c 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -776,20 +776,15 @@ vhost_attach_vdpa_device(int vid, struct rte_vdpa_device *vdpa_dev)
 }
 
 void
-vhost_set_ifname(int vid, const char *if_name, unsigned int if_len)
+vhost_set_ifname(int vid, const char *if_name)
 {
 	struct virtio_net *dev;
-	unsigned int len;
 
 	dev = get_device(vid);
 	if (dev == NULL)
 		return;
 
-	len = if_len > sizeof(dev->ifname) ?
-		sizeof(dev->ifname) : if_len;
-
-	strncpy(dev->ifname, if_name, len);
-	dev->ifname[sizeof(dev->ifname) - 1] = '\0';
+	strlcpy(dev->ifname, if_name, sizeof(dev->ifname));
 }
 
 void
@@ -915,8 +910,7 @@ rte_vhost_get_ifname(int vid, char *buf, size_t len)
 
 	len = RTE_MIN(len, sizeof(dev->ifname));
 
-	strncpy(buf, dev->ifname, len);
-	buf[len - 1] = '\0';
+	strlcpy(buf, dev->ifname, len);
 
 	return 0;
 }
diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index ee61f7415e..1c957d2929 100644
--- a/lib/vhost/vhost.h
+++ b/lib/vhost/vhost.h
@@ -877,7 +877,7 @@ int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
 
 void vhost_attach_vdpa_device(int vid, struct rte_vdpa_device *dev);
 
-void vhost_set_ifname(int, const char *if_name, unsigned int if_len);
+void vhost_set_ifname(int, const char *if_name);
 void vhost_setup_virtio_net(int vid, bool enable, bool legacy_ol_flags, bool stats_enabled,
 	bool support_iommu);
 void vhost_enable_extbuf(int vid);
-- 
2.53.0

Re: [PATCH 0/3] lib: remove use of strncpy

[fengchengwen]

Series-reviewed-by: Chengwen Feng <fengchengwen@huawei.com>

On 6/23/2026 10:19 PM, Bruce Richardson wrote:
> Taking a lead from the kernel, which has just finished a multi-year
> effort to remove use of strncpy[1], rework DPDK to remove use of the
> same function. This series removes all remaining uses of strncpy
> in lib directory.
> 
> [1] https://www.phoronix.com/news/Linux-7.2-Drops-strncpy
> 
> Bruce Richardson (3):
>   ethdev: remove use of strncpy
>   eventdev: improve bounds checks for names in adapter create
>   vhost: remove use of strncpy
> 
>  lib/ethdev/ethdev_driver.c              |  7 ++++++-
>  lib/eventdev/rte_event_eth_tx_adapter.c |  4 ++--
>  lib/vhost/socket.c                      |  4 +---
>  lib/vhost/vduse.c                       |  2 +-
>  lib/vhost/vhost.c                       | 12 +++---------
>  lib/vhost/vhost.h                       |  2 +-
>  6 files changed, 14 insertions(+), 17 deletions(-)
> 
> --
> 2.53.0
> 

Re: [PATCH 1/3] ethdev: remove use of strncpy

[Andrew Rybchenko]

On 6/23/26 5:19 PM, Bruce Richardson wrote:
> The use of strncpy is not generally recommended, so replace it in code
> tokenizing the representor list. Since its use in the function is not
> involving null-terminated strings (we know that copied block will
> not involve a null value in it), we can replace strncpy with memcpy
> rather than a string function. This keeps the original intent of the
> code.
> 
> For extra safety, also add in an explicit bounds check on the length
> value before doing the memcpy.
> 
> Fixes: 9a9eb104edf6 ("ethdev: parse multiple representor devargs")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>

[PATCH v2 0/3] lib: remove use of strncpy

[Bruce Richardson]

Taking a lead from the kernel, which has just finished a multi-year
effort to remove use of strncpy[1], rework DPDK to remove use of the
same function. This series removes all remaining uses of strncpy
in lib directory.

[1] https://www.phoronix.com/news/Linux-7.2-Drops-strncpy

V2: resubmit for 26.11, applying the series-reviewed-by as individual
    per-patch tags.

Bruce Richardson (3):
  ethdev: remove use of strncpy
  eventdev: improve bounds checks for names in adapter create
  vhost: remove use of strncpy

 lib/ethdev/ethdev_driver.c              |  7 ++++++-
 lib/eventdev/rte_event_eth_tx_adapter.c |  4 ++--
 lib/vhost/socket.c                      |  4 +---
 lib/vhost/vduse.c                       |  2 +-
 lib/vhost/vhost.c                       | 12 +++---------
 lib/vhost/vhost.h                       |  2 +-
 6 files changed, 14 insertions(+), 17 deletions(-)

-- 
2.53.0

[PATCH v2 1/3] ethdev: remove use of strncpy

[Bruce Richardson]

The use of strncpy is not generally recommended, so replace it in code
tokenizing the representor list. Since its use in the function is not
involving null-terminated strings (we know that copied block will
not involve a null value in it), we can replace strncpy with memcpy
rather than a string function. This keeps the original intent of the
code.

For extra safety, also add in an explicit bounds check on the length
value before doing the memcpy.

Fixes: 9a9eb104edf6 ("ethdev: parse multiple representor devargs")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Chengwen Feng <fengchengwen@huawei.com>
---
 lib/ethdev/ethdev_driver.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/ethdev/ethdev_driver.c b/lib/ethdev/ethdev_driver.c
index eab5c15d12..e6f8d6fe85 100644
--- a/lib/ethdev/ethdev_driver.c
+++ b/lib/ethdev/ethdev_driver.c
@@ -583,10 +583,15 @@ eth_dev_tokenise_representor_list(char *p_val, struct rte_eth_devargs *eth_devar
 		return devargs;
 	}
 
+	/* len - 2 strips the outer '[' and ']'; guard against underflow and overflow */
+	if (len < 2 || (len - 2) >= BUFSIZ) {
+		RTE_ETHDEV_LOG_LINE(ERR, "Representor list too long or malformed: %s", p_val);
+		return -EINVAL;
+	}
 	memset(str, 0, BUFSIZ);
 	memset(da_val, 0, BUFSIZ);
 	/* Remove the exterior [] of the consolidated list */
-	strncpy(str, &p_val[1], len - 2);
+	memcpy(str, &p_val[1], len - 2);
 	while (1) {
 		if (str[i] == '\0') {
 			if (da_val[0] != '\0') {
-- 
2.53.0

[PATCH v2 2/3] eventdev: improve bounds checks for names in adapter create

[Bruce Richardson]

The bounds checks for snprintf and then strncpy used different constant
defines, which happened to resolve to the same value (32). Make this
code more resilient by using sizeof() operator rather than the defines,
and replace use of strncpy with the better strlcpy.

Fixes: a3bbf2e09756 ("eventdev: add eth Tx adapter implementation")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Chengwen Feng <fengchengwen@huawei.com>
---
 lib/eventdev/rte_event_eth_tx_adapter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/eventdev/rte_event_eth_tx_adapter.c b/lib/eventdev/rte_event_eth_tx_adapter.c
index 91c7be55c7..d531da5d69 100644
--- a/lib/eventdev/rte_event_eth_tx_adapter.c
+++ b/lib/eventdev/rte_event_eth_tx_adapter.c
@@ -748,7 +748,7 @@ txa_service_adapter_create_ext(uint8_t id, struct rte_eventdev *dev,
 		return -EINVAL;
 
 	socket_id = dev->data->socket_id;
-	snprintf(mem_name, TXA_MEM_NAME_LEN,
+	snprintf(mem_name, sizeof(mem_name),
 		"rte_event_eth_txa_%d",
 		id);
 
@@ -767,7 +767,7 @@ txa_service_adapter_create_ext(uint8_t id, struct rte_eventdev *dev,
 	txa->id = id;
 	txa->eventdev_id = dev->data->dev_id;
 	txa->socket_id = socket_id;
-	strncpy(txa->mem_name, mem_name, TXA_SERVICE_NAME_LEN);
+	strlcpy(txa->mem_name, mem_name, sizeof(txa->mem_name));
 	txa->conf_cb = conf_cb;
 	txa->conf_arg = conf_arg;
 	txa->service_id = TXA_INVALID_SERVICE_ID;
-- 
2.53.0

[PATCH v2 3/3] vhost: remove use of strncpy

[Bruce Richardson]

The strlcpy is preferred over use of strncpy, which removes the need to
try and explicitly null-terminate some string buffers. We can also
simplify some name length handling as a result of this, as we no longer
need to use strnlen to clamp the length before calling the set_ifname
function.

Fixes: a277c7159876 ("vhost: refactor code structure")
Fixes: 0adb8eccc6a6 ("vhost: add VDUSE device creation and destruction")
Fixes: c171a2d5ff17 ("vhost: use strlcpy instead of strncpy")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Chengwen Feng <fengchengwen@huawei.com>
---
 lib/vhost/socket.c |  4 +---
 lib/vhost/vduse.c  |  2 +-
 lib/vhost/vhost.c  | 12 +++---------
 lib/vhost/vhost.h  |  2 +-
 4 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/lib/vhost/socket.c b/lib/vhost/socket.c
index 70e582a18d..0943b3e9bb 100644
--- a/lib/vhost/socket.c
+++ b/lib/vhost/socket.c
@@ -207,7 +207,6 @@ static void
 vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 {
 	int vid;
-	size_t size;
 	struct vhost_user_connection *conn;
 	int ret;
 	struct virtio_net *dev;
@@ -226,8 +225,7 @@ vhost_user_add_connection(int fd, struct vhost_user_socket *vsocket)
 		goto err;
 	}
 
-	size = strnlen(vsocket->path, PATH_MAX);
-	vhost_set_ifname(vid, vsocket->path, size);
+	vhost_set_ifname(vid, vsocket->path);
 
 	vhost_setup_virtio_net(vid, vsocket->use_builtin_virtio_net,
 		vsocket->net_compliant_ol_flags, vsocket->stats_enabled,
diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
index 0b5d158fee..f8a4a8edcb 100644
--- a/lib/vhost/vduse.c
+++ b/lib/vhost/vduse.c
@@ -796,7 +796,7 @@ vduse_device_create(const char *path, bool compliant_ol_flags, bool extbuf, bool
 		goto out_dev_destroy;
 	}
 
-	strncpy(dev->ifname, path, IF_NAME_SZ - 1);
+	strlcpy(dev->ifname, path, sizeof(dev->ifname));
 	dev->vduse_ctrl_fd = control_fd;
 	dev->vduse_dev_fd = dev_fd;
 
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 7e68b2c3be..fde8acb00c 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -776,20 +776,15 @@ vhost_attach_vdpa_device(int vid, struct rte_vdpa_device *vdpa_dev)
 }
 
 void
-vhost_set_ifname(int vid, const char *if_name, unsigned int if_len)
+vhost_set_ifname(int vid, const char *if_name)
 {
 	struct virtio_net *dev;
-	unsigned int len;
 
 	dev = get_device(vid);
 	if (dev == NULL)
 		return;
 
-	len = if_len > sizeof(dev->ifname) ?
-		sizeof(dev->ifname) : if_len;
-
-	strncpy(dev->ifname, if_name, len);
-	dev->ifname[sizeof(dev->ifname) - 1] = '\0';
+	strlcpy(dev->ifname, if_name, sizeof(dev->ifname));
 }
 
 void
@@ -915,8 +910,7 @@ rte_vhost_get_ifname(int vid, char *buf, size_t len)
 
 	len = RTE_MIN(len, sizeof(dev->ifname));
 
-	strncpy(buf, dev->ifname, len);
-	buf[len - 1] = '\0';
+	strlcpy(buf, dev->ifname, len);
 
 	return 0;
 }
diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index ee61f7415e..1c957d2929 100644
--- a/lib/vhost/vhost.h
+++ b/lib/vhost/vhost.h
@@ -877,7 +877,7 @@ int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
 
 void vhost_attach_vdpa_device(int vid, struct rte_vdpa_device *dev);
 
-void vhost_set_ifname(int, const char *if_name, unsigned int if_len);
+void vhost_set_ifname(int, const char *if_name);
 void vhost_setup_virtio_net(int vid, bool enable, bool legacy_ol_flags, bool stats_enabled,
 	bool support_iommu);
 void vhost_enable_extbuf(int vid);
-- 
2.53.0