[ 75/82] batman-adv: Only write requested number of byte to user buffer

Ben Hutchings
2013-03-18T04:47:16Z

From: Sven Eckelmann <sven@narfation.org>

commit b5a1eeef04cc7859f34dec9b72ea1b28e4aba07c upstream.

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>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/batman-adv/icmp_socket.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -136,10 +136,9 @@ static ssize_t bat_socket_read(struct fi

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)