[ 029/143] net: heap overflow in __audit_sockaddr()

Willy Tarreau
2014-05-12T01:44:31Z

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2.6.32-longterm review patch. If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 1661bf364ae9c506bc8795fef70d1532931be1e8 ]

We need to cap ->msg_namelen or it leads to a buffer overflow when we
to the memcpy() in __audit_sockaddr(). It requires CAP_AUDIT_CONTROL to
exploit this bug.

The call tree is:
___sys_recvmsg()
move_addr_to_user()
audit_sockaddr()
__audit_sockaddr()

Reported-by: Jüri Aedla <juri.aedla@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[wt: 2.6.32: msg_sys is a struct, not a pointer]
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
net/compat.c | 2 ++
net/socket.c | 24 ++++++++++++++++++++----
2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/net/compat.c b/net/compat.c
index 9559afc..da3d0fc 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -69,6 +69,8 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
__get_user(kmsg->msg_controllen, &umsg->msg_controllen) ||
__get_user(kmsg->msg_flags, &umsg->msg_flags))
return -EFAULT;
+ if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+ return -EINVAL;
kmsg->msg_name = compat_ptr(tmp1);
kmsg->msg_iov = compat_ptr(tmp2);
kmsg->msg_control = compat_ptr(tmp3);
diff --git a/net/socket.c b/net/socket.c
index bf9fc68..9f8cd74 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1863,6 +1863,16 @@ SYSCALL_DEFINE2(shutdown, int, fd, int, how)
#define COMPAT_NAMELEN(msg) COMPAT_MSG(msg, msg_namelen)
#define COMPAT_FLAGS(msg) COMPAT_MSG(msg, msg_flags)

+static int copy_msghdr_from_user(struct msghdr *kmsg,
+ struct msghdr __user *umsg)
+{
+ if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
+ return -EFAULT;
+ if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+ return -EINVAL;
+ return 0;
+}
+
/*
* BSD sendmsg interface
*/
@@ -1887,8 +1897,11 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct msghdr __user *, msg, unsigned, flags)
if (get_compat_msghdr(&msg_sys, msg_compat))
return -EFAULT;
}
- else if (copy_from_user(&msg_sys, msg, sizeof(struct msghdr)))
- return -EFAULT;
+ else {
+ err = copy_msghdr_from_user(&msg_sys, msg);
+ if (err)
+ return err;
+ }

sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
@@ -1997,8 +2010,11 @@ SYSCALL_DEFINE3(recvmsg, int, fd, struct msghdr __user *, msg,
if (get_compat_msghdr(&msg_sys, msg_compat))
return -EFAULT;
}
- else if (copy_from_user(&msg_sys, msg, sizeof(struct msghdr)))
- return -EFAULT;
+ else {
+ err = copy_msghdr_from_user(&msg_sys, msg);
+ if (err)
+ return err;
+ }

sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
--
1.7.12.2.21.g234cd45.dirty