[PATCH] net: socket: error on a negative msg_namelen

[PATCH] net: socket: error on a negative msg_namelen

[Matthew Leach]

When copying in a struct msghdr from the user, if the user has set the
msg_namelen parameter to a negative value it gets clamped to a valid
size due to a comparison between signed and unsigned values.

Ensure the syscall errors when the user passes in a negative value.

Signed-off-by: Matthew Leach <matthew.leach@arm.com>
---
 net/socket.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/socket.c b/net/socket.c
index 879933a..32df584 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1985,6 +1985,10 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
 {
 	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
 		return -EFAULT;
+
+	if (kmsg->msg_namelen < 0)
+		return -EINVAL;
+
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
 		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	return 0;
-- 
1.8.5.3

Re: [PATCH] net: socket: error on a negative msg_namelen

[David Miller]

From: Matthew Leach <matthew.leach@arm.com>
Date: Tue, 11 Mar 2014 11:58:27 +0000

> When copying in a struct msghdr from the user, if the user has set the
> msg_namelen parameter to a negative value it gets clamped to a valid
> size due to a comparison between signed and unsigned values.
> 
> Ensure the syscall errors when the user passes in a negative value.
> 
> Signed-off-by: Matthew Leach <matthew.leach@arm.com>

Applied and queued up for -stable, thanks.