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 and sprintf:
rpmsg/rpmsg_char.c
165: dev_err(dev, "failed to open %s\n", eptdev->chinfo.name);
368: return sprintf(buf, "%s\n", eptdev->chinfo.name);
... and with strcmp():
| static struct rpmsg_endpoint *qcom_glink_create_ept(struct rpmsg_device *rpdev,
| rpmsg_rx_cb_t cb,
| void *priv,
| struct rpmsg_channel_info
| chinfo)
| ...
| const char *name = chinfo.name;
| ...
| if (!strcmp(channel->name, name))
Since chinfo is initialized as such (just above the strscpy()):
| struct rpmsg_channel_info chinfo = {
| .src = rpwwan->rpdev->src,
| .dst = RPMSG_ADDR_ANY,
| };
... we know other members are zero-initialized. This means no
NUL-padding is required (as any NUL-byte assignments are redundant).
Considering the above, a suitable replacement is `strscpy` due to the
fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.
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: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
Changes in v2:
- clarify chinfo _is_ zero-init'd in commit msg (thanks Stephan)
- use strscpy instead (thanks Kees, Stephan)
- Link to v1: https://lore.kernel.org/r/20231018-strncpy-drivers-net-wwan-rpmsg_wwan_ctrl-c-v1-1-4e343270373a@xxxxxxxxxx
---
Note: found with grep
Note: build-tested only
I've rolled Kees' RB into this patch from v1 as it matches his previous
review.
---
drivers/net/wwan/rpmsg_wwan_ctrl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wwan/rpmsg_wwan_ctrl.c b/drivers/net/wwan/rpmsg_wwan_ctrl.c
index 86b60aadfa11..26756ff0e44d 100644
--- a/drivers/net/wwan/rpmsg_wwan_ctrl.c
+++ b/drivers/net/wwan/rpmsg_wwan_ctrl.c
@@ -37,7 +37,7 @@ static int rpmsg_wwan_ctrl_start(struct wwan_port *port)
.dst = RPMSG_ADDR_ANY,
};
- strncpy(chinfo.name, rpwwan->rpdev->id.name, RPMSG_NAME_SIZE);
+ strscpy(chinfo.name, rpwwan->rpdev->id.name, sizeof(chinfo.name));
rpwwan->ept = rpmsg_create_ept(rpwwan->rpdev, rpmsg_wwan_ctrl_callback,
rpwwan, chinfo);
if (!rpwwan->ept)
---
base-commit: 58720809f52779dc0f08e53e54b014209d13eebb
change-id: 20231018-strncpy-drivers-net-wwan-rpmsg_wwan_ctrl-c-3f620aafd326
Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>
