| From bc909d9ddbf7778371e36a651d6e4194b1cc7d4c Mon Sep 17 00:00:00 2001 |
| From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| Date: Wed, 24 Aug 2011 19:45:03 -0700 |
| Subject: sendmmsg/sendmsg: fix unsafe user pointer access |
| |
| From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| |
| commit bc909d9ddbf7778371e36a651d6e4194b1cc7d4c upstream. |
| |
| 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.desnoyers@efficios.com> |
| Signed-off-by: David Goulet <dgoulet@ev0ke.net> |
| CC: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
| CC: Anton Blanchard <anton@samba.org> |
| CC: David S. Miller <davem@davemloft.net> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| net/socket.c | 10 ++++++---- |
| 1 file changed, 6 insertions(+), 4 deletions(-) |
| |
| --- a/net/socket.c |
| +++ b/net/socket.c |
| @@ -1965,8 +1965,9 @@ static int __sys_sendmsg(struct socket * |
| * 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 * |
| */ |
| 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: |
