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batman-adv: Only write requested number of byte to user buffer

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 <>
Signed-off-by: Marek Lindner <>
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ecsv authored and Marek Lindner committed Dec 10, 2011
1 parent d18eb45 commit b5a1eeef04cc7859f34dec9b72ea1b28e4aba07c
Showing with 2 additions and 3 deletions.
  1. +2 −3 net/batman-adv/icmp_socket.c
@@ -136,10 +136,9 @@ static ssize_t bat_socket_read(struct file *file, char __user *buf,
- 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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