[B.A.T.M.A.N.] [PATCHv3 3/3] batman-adv: Only write requested number of byte to user buffer

[Sven Eckelmann <sven@narfation.org>]

Don't write more than the requested number of bytes of an batman-adv icmp
packet to the userspace buffer. Otherwise unrelated userspace memory might get
overridden by the kernel.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 icmp_socket.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/icmp_socket.c b/icmp_socket.c
index 4dc55e8..5d69e10 100644
--- a/icmp_socket.c
+++ b/icmp_socket.c
@@ -136,10 +136,9 @@ static ssize_t bat_socket_read(struct file *file, char __user *buf,
 
 	spin_unlock_bh(&socket_client->lock);
 
-	error = copy_to_user(buf, &socket_packet->icmp_packet,
-			     socket_packet->icmp_len);
+	packet_len = min(count, socket_packet->icmp_len);
+	error = copy_to_user(buf, &socket_packet->icmp_packet, packet_len);
 
-	packet_len = socket_packet->icmp_len;
 	kfree(socket_packet);
 
 	if (error)
-- 
1.7.7.3