2023-10-20 23:19:10

by Justin Stitt

[permalink] [raw]
Subject: [PATCH] rpmsg: replace deprecated strncpy with strscpy_pad

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect chinfo.name to be NUL-terminated based on its use with format
strings:
| dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);

Since chinfo is not default initialized, we should NUL-pad the `name`
field so that the behavior is consistent with what strncpy() provides:
| struct rpmsg_channel_info chinfo;

Considering the above, a suitable replacement is `strscpy_pad` due to
the fact that it guarantees both NUL-termination and NUL-padding on the
destination buffer.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
drivers/rpmsg/rpmsg_ns.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
index c70ad03ff2e9..bde8c8d433e0 100644
--- a/drivers/rpmsg/rpmsg_ns.c
+++ b/drivers/rpmsg/rpmsg_ns.c
@@ -50,7 +50,7 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
/* don't trust the remote processor for null terminating the name */
msg->name[RPMSG_NAME_SIZE - 1] = '\0';

- strncpy(chinfo.name, msg->name, sizeof(chinfo.name));
+ strscpy_pad(chinfo.name, msg->name, sizeof(chinfo.name));
chinfo.src = RPMSG_ADDR_ANY;
chinfo.dst = rpmsg32_to_cpu(rpdev, msg->addr);


---
base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c
change-id: 20231020-strncpy-drivers-rpmsg-rpmsg_ns-c-ffe3fa2bb9ff

Best regards,
--
Justin Stitt <[email protected]>