commit: bc909d9ddbf7778371e36a651d6e4194b1cc7d4c
From: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Date: Wed, 24 Aug 2011 19:45:03 -0700
Subject: [PATCH] sendmmsg/sendmsg: fix unsafe user pointer access
Dereferencing a user pointer directly from kernel-space without going
through the copy_from_user family of functions is a bad idea. Two of
such usages can be found in the sendmsg code path called from sendmmsg,
added by
commit c71d8ebe7a4496fb7231151cb70a6baa0cb56f9a upstream.
commit 5b47b8038f183b44d2d8ff1c7d11a5c1be706b34 in the 3.0-stable tree.
Usages are performed through memcmp() and memcpy() directly. Fix those
by using the already copied msg_sys structure instead of the __user *msg
structure. Note that msg_sys can be set to NULL by verify_compat_iovec()
or verify_iovec(), which requires additional NULL pointer checks.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Signed-off-by: David Goulet <dgou...@ev0ke.net>
CC: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
CC: Anton Blanchard <an...@samba.org>
CC: David S. Miller <da...@davemloft.net>
CC: stable <sta...@kernel.org>
Signed-off-by: David S. Miller <da...@davemloft.net>
---
net/socket.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/socket.c b/net/socket.c
index 24a7740..ffe92ca 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1965,8 +1965,9 @@ static int __sys_sendmsg(struct socket *sock, struct
msghdr __user *msg,
* used_address->name_len is initialized to UINT_MAX so that the first
* destination address never matches.
*/
- if (used_address && used_address->name_len == msg_sys->msg_namelen &&
- !memcmp(&used_address->name, msg->msg_name,
+ if (used_address && msg_sys->msg_name &&
+ used_address->name_len == msg_sys->msg_namelen &&
+ !memcmp(&used_address->name, msg_sys->msg_name,
used_address->name_len)) {
err = sock_sendmsg_nosec(sock, msg_sys, total_len);
goto out_freectl;
@@ -1978,8 +1979,9 @@ static int __sys_sendmsg(struct socket *sock, struct
msghdr __user *msg,
*/
if (used_address && err >= 0) {
used_address->name_len = msg_sys->msg_namelen;
- memcpy(&used_address->name, msg->msg_name,
- used_address->name_len);
+ if (msg_sys->msg_name)
+ memcpy(&used_address->name, msg_sys->msg_name,
+ used_address->name_len);
}
out_freectl:
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