eeprom: idt_89hpesx: replace open-coded kmemdup_nul

A malloc + strncpy + manual NUL_termination is just kmemdup_nul. Let's use
this interface as it is less error-prone and more readable.

Also drop `csraddr_len` as it is just used in a single place and we can
just do the arithmetic in-line.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230927-strncpy-drivers-misc-eeprom-idt_89hpesx-c-v1-1-08e3d45b8c05@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/eeprom/idt_89hpesx.c b/drivers/misc/eeprom/idt_89hpesx.c
index 1d1f30b5c4269a17255f5b33dfda180ea256738b..d807d08e26144f861c99b42544d4b7ae54a8517c 100644 (file)
--- a/drivers/misc/eeprom/idt_89hpesx.c
+++ b/drivers/misc/eeprom/idt_89hpesx.c
@@ -905,7 +905,7 @@ static ssize_t idt_dbgfs_csr_write(struct file *filep, const char __user *ubuf,
 {
        struct idt_89hpesx_dev *pdev = filep->private_data;
        char *colon_ch, *csraddr_str, *csrval_str;
-       int ret, csraddr_len;
+       int ret;
        u32 csraddr, csrval;
        char *buf;
 
@@ -927,21 +927,16 @@ static ssize_t idt_dbgfs_csr_write(struct file *filep, const char __user *ubuf,
         * no new CSR value
         */
        if (colon_ch != NULL) {
-               csraddr_len = colon_ch - buf;
-               csraddr_str =
-                       kmalloc(csraddr_len + 1, GFP_KERNEL);
+               /* Copy the register address to the substring buffer */
+               csraddr_str = kmemdup_nul(buf, colon_ch - buf, GFP_KERNEL);
                if (csraddr_str == NULL) {
                        ret = -ENOMEM;
                        goto free_buf;
                }
-               /* Copy the register address to the substring buffer */
-               strncpy(csraddr_str, buf, csraddr_len);
-               csraddr_str[csraddr_len] = '\0';
                /* Register value must follow the colon */
                csrval_str = colon_ch + 1;
        } else /* if (str_colon == NULL) */ {
                csraddr_str = (char *)buf; /* Just to shut warning up */
-               csraddr_len = strnlen(csraddr_str, count);
                csrval_str = NULL;
        }