[B.A.T.M.A.N.] [PATCHv3 1/2] batman-adv: Only write requested number of byte to user buffer

Sven Eckelmann
2011-12-10T15:36:01Z

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
overwritten by the kernel.

Reported-by: Paul Kot <pawlkt@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
Marek pointed out that it is better to merge patch 1 and 2. I think it doesn't
make sense to leave Paul Kot as author because it doesn't look like his patch
at all.

And thanks to Andrew for s/overridden/overwritten/

icmp_socket.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/icmp_socket.c b/icmp_socket.c
index 5bc8649..66923d2 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