scsi: devinfo: Replace strncpy() and manual pad

Depending on the state of @compatible, we are going to do different things
with our @to buffer.

When @compatible is true we want a NUL-term'd and NUL-padded destination
buffer. Conversely, if @compatible is false we just want a space-padded
destination buffer (no NUL-term required).

As per:
/**
 * scsi_dev_info_list_add_keyed - add one dev_info list entry.
 * @compatible: if true, null terminate short strings.  Otherwise space pad.
...

Note that we can't easily use strtomem_pad() here as the size of the @to
buffer is unknown to the compiler due to indirection layers.

Now, the intent of the code is more clear (I probably didn't even need
to add a comment -- that's how clear it is).

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240305-strncpy-drivers-scsi-mpi3mr-mpi3mr_fw-c-v3-5-5b78a13ff984@google.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c
index ba7237e838633c95528c742db4efc94d209ecc0f..a7071e71389e0533ab367910b74b75ba1b452f58 100644 (file)
--- a/drivers/scsi/scsi_devinfo.c
+++ b/drivers/scsi/scsi_devinfo.c
@@ -293,14 +293,16 @@ static void scsi_strcpy_devinfo(char *name, char *to, size_t to_length,
        size_t from_length;
 
        from_length = strlen(from);
-       /* This zero-pads the destination */
-       strncpy(to, from, to_length);
-       if (from_length < to_length && !compatible) {
-               /*
-                * space pad the string if it is short.
-                */
-               memset(&to[from_length], ' ', to_length - from_length);
-       }
+
+       /*
+        * null pad and null terminate if compatible
+        * otherwise space pad
+        */
+       if (compatible)
+               strscpy_pad(to, from, to_length);
+       else
+               memcpy_and_pad(to, to_length, from, from_length, ' ');
+
        if (from_length > to_length)
                 printk(KERN_WARNING "%s: %s string '%s' is too long\n",
                        __func__, name, from);