Hello Mark Pearson,
The patch a7314b3b1d8a: "platform/x86: think-lmi: Add WMI interface
support on Lenovo platforms" from May 30, 2021, leads to the
following static checker warning:
drivers/platform/x86/think-lmi.c:453 kbdlang_store()
error: iterator underflow 'setting->kbdlang' (-1),1-3
drivers/platform/x86/think-lmi.c
438 static ssize_t kbdlang_store(struct kobject *kobj,
439 struct kobj_attribute *attr,
440 const char *buf, size_t count)
441 {
442 struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
443 int length;
444
445 length = strlen(buf);
"count" can never be zero, but strlen(buf) can be zero.
446 if (buf[length-1] == '\n')
^^^^^^^^
So this code can read before the start of the buffer, potentially
leading to an Oops.
447 length--;
448
449 if (!length || (length >= TLMI_LANG_MAXLEN))
450 return -EINVAL;
451
452 memcpy(setting->kbdlang, buf, length);
453 setting->kbdlang[length] = '\0';
454 return count;
455 }
regards,
dan carpenter
