[PATCH 03/64] rpmsg: glink: Replace strncpy() with strscpy_pad()

Kees Cook
2021-07-27T21:01:22Z

The use of strncpy() is considered deprecated for NUL-terminated
strings[1]. Replace strncpy() with strscpy_pad() (as it seems this case
expects the NUL padding to fill the allocation following the flexible
array). This additionally silences a warning seen when building under
-Warray-bounds:

./include/linux/fortify-string.h:38:30: warning: '__builtin_strncpy' offset 24 from the object at '__mptr' is out of the bounds of referenced subobject 'data' with type 'u8[]' {aka 'unsigned char[]'} at offset 24 [-Warray-bounds]
38 | #define __underlying_strncpy __builtin_strncpy
| ^
./include/linux/fortify-string.h:50:9: note: in expansion of macro '__underlying_strncpy'
50 | return __underlying_strncpy(p, q, size);
| ^~~~~~~~~~~~~~~~~~~~
drivers/rpmsg/qcom_glink_native.c: In function 'qcom_glink_work':
drivers/rpmsg/qcom_glink_native.c:36:5: note: subobject 'data' declared here
36 | u8 data[];
| ^~~~

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings

Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/rpmsg/qcom_glink_native.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 05533c71b10e..c7b9de655080 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1440,7 +1440,7 @@ static int qcom_glink_rx_open(struct qcom_glink *glink, unsigned int rcid,
}

rpdev->ept = &channel->ept;
- strncpy(rpdev->id.name, name, RPMSG_NAME_SIZE);
+ strscpy_pad(rpdev->id.name, name, RPMSG_NAME_SIZE);
rpdev->src = RPMSG_ADDR_ANY;
rpdev->dst = RPMSG_ADDR_ANY;
rpdev->ops = &glink_device_ops;
--
2.30.2