diff options
| author | Jan Kara <jack@suse.cz> | 2015-06-02 12:38:39 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-06-15 10:51:12 +0200 |
| commit | 8cb81811e924ff0214ce4e8344e2feb1549cf0ce (patch) | |
| tree | 4bb8a52ff2121d335f893ad2d2cf4bfa89e47ece | |
| parent | 2e4aa2f2bdcf9b80bace0b0c460bd407d76f49d3 (diff) | |
s390/keyboard: avoid off-by-one when using strnlen_user()
strnlen_user() returns the length of the string including terminating 0.
So avoid counting it again and unnecessarily reducing maximum string
size by 1.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | drivers/s390/char/keyboard.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c index 01463b052ae7..ef04a9f7a704 100644 --- a/drivers/s390/char/keyboard.c +++ b/drivers/s390/char/keyboard.c @@ -433,20 +433,23 @@ do_kdgkb_ioctl(struct kbd_data *kbd, struct kbsentry __user *u_kbs, case KDSKBSENT: if (!perm) return -EPERM; - len = strnlen_user(u_kbs->kb_string, - sizeof(u_kbs->kb_string) - 1); + len = strnlen_user(u_kbs->kb_string, sizeof(u_kbs->kb_string)); if (!len) return -EFAULT; - if (len > sizeof(u_kbs->kb_string) - 1) + if (len > sizeof(u_kbs->kb_string)) return -EINVAL; - p = kmalloc(len + 1, GFP_KERNEL); + p = kmalloc(len, GFP_KERNEL); if (!p) return -ENOMEM; if (copy_from_user(p, u_kbs->kb_string, len)) { kfree(p); return -EFAULT; } - p[len] = 0; + /* + * Make sure the string is terminated by 0. User could have + * modified it between us running strnlen_user() and copying it. + */ + p[len - 1] = 0; kfree(kbd->func_table[kb_func]); kbd->func_table[kb_func] = p; break; |