diff options
| -rw-r--r-- | include/linux/rfkill.h | 14 | ||||
| -rw-r--r-- | net/rfkill/core.c | 10 |
2 files changed, 22 insertions, 2 deletions
diff --git a/include/linux/rfkill.h b/include/linux/rfkill.h index 2ce29831feb6..f3d5812693d6 100644 --- a/include/linux/rfkill.h +++ b/include/linux/rfkill.h @@ -82,6 +82,20 @@ struct rfkill_event { __u8 soft, hard; } __packed; +/* + * We are planning to be backward and forward compatible with changes + * to the event struct, by adding new, optional, members at the end. + * When reading an event (whether the kernel from userspace or vice + * versa) we need to accept anything that's at least as large as the + * version 1 event size, but might be able to accept other sizes in + * the future. + * + * One exception is the kernel -- we already have two event sizes in + * that we've made the 'hard' member optional since our only option + * is to ignore it anyway. + */ +#define RFKILL_EVENT_SIZE_V1 8 + /* ioctl for turning off rfkill-input (if present) */ #define RFKILL_IOC_MAGIC 'R' #define RFKILL_IOC_NOINPUT 1 diff --git a/net/rfkill/core.c b/net/rfkill/core.c index 79693fe2001e..47497c97c8d9 100644 --- a/net/rfkill/core.c +++ b/net/rfkill/core.c @@ -1076,10 +1076,16 @@ static ssize_t rfkill_fop_write(struct file *file, const char __user *buf, struct rfkill_event ev; /* we don't need the 'hard' variable but accept it */ - if (count < sizeof(ev) - 1) + if (count < RFKILL_EVENT_SIZE_V1 - 1) return -EINVAL; - if (copy_from_user(&ev, buf, sizeof(ev) - 1)) + /* + * Copy as much data as we can accept into our 'ev' buffer, + * but tell userspace how much we've copied so it can determine + * our API version even in a write() call, if it cares. + */ + count = min(count, sizeof(ev)); + if (copy_from_user(&ev, buf, count)) return -EFAULT; if (ev.op != RFKILL_OP_CHANGE && ev.op != RFKILL_OP_CHANGE_ALL) |