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-rw-r--r--net/rfkill/core.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/net/rfkill/core.c b/net/rfkill/core.c
index 2fc4a1724eb8..044de1c6af3d 100644
--- a/net/rfkill/core.c
+++ b/net/rfkill/core.c
@@ -1091,10 +1091,16 @@ 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)