[PATCH net-next v4] tipc: replace deprecated strcpy with strscpy in tipc_bearer_get_name()

[Ajith P V]

The `strcpy()` function is deprecated and moving towards code-tree
elimination. Replacing it with `strscpy()` fixes potential buffer
overflow vectors by ensuring safe NULL-termination based on the
destination buffer size limit [1][2].

To make the interface safer and more robust for future callers, refactor
`tipc_bearer_get_name()` to accept a destination buffer length parameter.
Replace `strcpy()` with `strscpy()` and pass through any potential
`-E2BIG` truncation error code up to the caller. Update the existing
caller in `net/tipc/monitor.c` to pass its array size.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Link: https://github.com/KSPP/linux/issues/88 [2]

Signed-off-by: Ajith P V <ajithpv.linux@xxxxxxxxx>
---
v4:
  - Avoid hard-coding TIPC_MAX_BEARER_NAME in the function body.
  - Pass size_t len from the caller down to strscpy().
  - Forward strscpy()'s -E2BIG error up through the existing int return type.
  - Updated function documentation comment block.
v3:
  - Fix patch title as suggested by Tung Quang Nguyen.
  - No code changes from v2.
v2:
  - Target net-next tree instead of standard net tree as requested by Tung Quang Nguyen.
  - No code changes from v1.

 net/tipc/bearer.c  | 8 ++++++--
 net/tipc/bearer.h  | 2 +-
 net/tipc/monitor.c | 2 +-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 05dcd2f9e887..abd90e6bde09 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -195,12 +195,14 @@ struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name)
 /*     tipc_bearer_get_name - get the bearer name from its id.
  *     @net: network namespace
  *     @name: a pointer to the buffer where the name will be stored.
+ *     @len: size of the destination buffer
  *     @bearer_id: the id to get the name from.
  */
-int tipc_bearer_get_name(struct net *net, char *name, u32 bearer_id)
+int tipc_bearer_get_name(struct net *net, char *name, size_t len, u32 bearer_id)
 {
 	struct tipc_net *tn = tipc_net(net);
 	struct tipc_bearer *b;
+	int ret;
 
 	if (bearer_id >= MAX_BEARERS)
 		return -EINVAL;
@@ -209,7 +211,9 @@ int tipc_bearer_get_name(struct net *net, char *name, u32 bearer_id)
 	if (!b)
 		return -EINVAL;
 
-	strcpy(name, b->name);
+	ret = strscpy(name, b->name, len);
+	if (ret < 0)
+		return ret; /* Returns -E2BIG if destination buffer is too small */
 	return 0;
 }
 
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 41eac1ee0c09..12a322642de1 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -226,7 +226,7 @@ int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
 void tipc_bearer_add_dest(struct net *net, u32 bearer_id, u32 dest);
 void tipc_bearer_remove_dest(struct net *net, u32 bearer_id, u32 dest);
 struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name);
-int tipc_bearer_get_name(struct net *net, char *name, u32 bearer_id);
+int tipc_bearer_get_name(struct net *net, char *name, size_t len, u32 bearer_id);
 struct tipc_media *tipc_media_find(const char *name);
 int tipc_bearer_setup(void);
 void tipc_bearer_cleanup(void);
diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
index a94b9b36a700..8af49000a07c 100644
--- a/net/tipc/monitor.c
+++ b/net/tipc/monitor.c
@@ -833,7 +833,7 @@ int __tipc_nl_add_monitor(struct net *net, struct tipc_nl_msg *msg,
 	void *hdr;
 	int ret;
 
-	ret = tipc_bearer_get_name(net, bearer_name, bearer_id);
+	ret = tipc_bearer_get_name(net, bearer_name, sizeof(bearer_name), bearer_id);
 	if (ret || !mon)
 		return 0;
 
-- 
2.43.0