[PATCH 02/11] scsi: devinfo: rework scsi_strcpy_devinfo()

Arnd Bergmann
2024-03-28T14:05:46Z

From: Arnd Bergmann <arnd@arndb.de>

scsi_strcpy_devinfo() appears to work as intended but its semantics are
so confusing that gcc warns about it when -Wstringop-truncation is enabled:

In function 'scsi_strcpy_devinfo',
inlined from 'scsi_dev_info_list_add_keyed' at drivers/scsi/scsi_devinfo.c:370:2:
drivers/scsi/scsi_devinfo.c:297:9: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
297 | strncpy(to, from, to_length);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reorganize the function to completely separate the nul-terminated from
the space-padded/non-terminated case. The former is just strscpy_pad(),
while the latter does not have a standard function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/scsi/scsi_devinfo.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/scsi_devinfo.c b/drivers/scsi/scsi_devinfo.c
index ba7237e83863..58726c15ebac 100644
--- a/drivers/scsi/scsi_devinfo.c
+++ b/drivers/scsi/scsi_devinfo.c
@@ -290,18 +290,28 @@ static struct scsi_dev_info_list_table *scsi_devinfo_lookup_by_key(int key)
static void scsi_strcpy_devinfo(char *name, char *to, size_t to_length,
char *from, int compatible)
{
- size_t from_length;
+ int ret;

- 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);
+ if (compatible) {
+ /* This zero-pads and nul-terminates the destination */
+ ret = strscpy_pad(to, from, to_length);
+ } else {
+ /* no nul-termination but space-padding for short strings */
+ size_t from_length = strlen(from);
+ ret = from_length;
+
+ if (from_length > to_length) {
+ from_length = to_length;
+ ret = -E2BIG;
+ }
+
+ memcpy(to, from, from_length);
+
+ if (from_length < to_length)
+ memset(&to[from_length], ' ', to_length - from_length);
}
- if (from_length > to_length)
+
+ if (ret < 0)
printk(KERN_WARNING "%s: %s string '%s' is too long\n",
__func__, name, from);
}
--
2.39.2