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

From: Ben Hutchings
Date: Mon Mar 18 2013 - 00:47:50 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Sven Eckelmann <sven@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Signed-off-by: Marek Lindner <lindner_marek@xxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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


- 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;

if (error)

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