[ 067/167] [PATCH 07/26] phonet: Check input from user before allocating

Ben Hutchings
2012-05-09T06:03:39Z

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3.2-stable review patch. If anyone has any objections, please let me know.

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

From: Sasha Levin <levinsasha928@gmail.com>

[ Upstream commit bcf1b70ac6eb0ed8286c66e6bf37cb747cbaa04c ]

A phonet packet is limited to USHRT_MAX bytes, this is never checked during
tx which means that the user can specify any size he wishes, and the kernel
will attempt to allocate that size.

In the good case, it'll lead to the following warning, but it may also cause
the kernel to kick in the OOM and kill a random task on the server.

[ 8921.744094] WARNING: at mm/page_alloc.c:2255 __alloc_pages_slowpath+0x65/0x730()
[ 8921.749770] Pid: 5081, comm: trinity Tainted: G W 3.4.0-rc1-next-20120402-sasha #46
[ 8921.756672] Call Trace:
[ 8921.758185] [<ffffffff810b2ba7>] warn_slowpath_common+0x87/0xb0
[ 8921.762868] [<ffffffff810b2be5>] warn_slowpath_null+0x15/0x20
[ 8921.765399] [<ffffffff8117eae5>] __alloc_pages_slowpath+0x65/0x730
[ 8921.769226] [<ffffffff81179c8a>] ? zone_watermark_ok+0x1a/0x20
[ 8921.771686] [<ffffffff8117d045>] ? get_page_from_freelist+0x625/0x660
[ 8921.773919] [<ffffffff8117f3a8>] __alloc_pages_nodemask+0x1f8/0x240
[ 8921.776248] [<ffffffff811c03e0>] kmalloc_large_node+0x70/0xc0
[ 8921.778294] [<ffffffff811c4bd4>] __kmalloc_node_track_caller+0x34/0x1c0
[ 8921.780847] [<ffffffff821b0e3c>] ? sock_alloc_send_pskb+0xbc/0x260
[ 8921.783179] [<ffffffff821b3c65>] __alloc_skb+0x75/0x170
[ 8921.784971] [<ffffffff821b0e3c>] sock_alloc_send_pskb+0xbc/0x260
[ 8921.787111] [<ffffffff821b002e>] ? release_sock+0x7e/0x90
[ 8921.788973] [<ffffffff821b0ff0>] sock_alloc_send_skb+0x10/0x20
[ 8921.791052] [<ffffffff824cfc20>] pep_sendmsg+0x60/0x380
[ 8921.792931] [<ffffffff824cb4a6>] ? pn_socket_bind+0x156/0x180
[ 8921.794917] [<ffffffff824cb50f>] ? pn_socket_autobind+0x3f/0x90
[ 8921.797053] [<ffffffff824cb63f>] pn_socket_sendmsg+0x4f/0x70
[ 8921.798992] [<ffffffff821ab8e7>] sock_aio_write+0x187/0x1b0
[ 8921.801395] [<ffffffff810e325e>] ? sub_preempt_count+0xae/0xf0
[ 8921.803501] [<ffffffff8111842c>] ? __lock_acquire+0x42c/0x4b0
[ 8921.805505] [<ffffffff821ab760>] ? __sock_recv_ts_and_drops+0x140/0x140
[ 8921.807860] [<ffffffff811e07cc>] do_sync_readv_writev+0xbc/0x110
[ 8921.809986] [<ffffffff811958e7>] ? might_fault+0x97/0xa0
[ 8921.811998] [<ffffffff817bd99e>] ? security_file_permission+0x1e/0x90
[ 8921.814595] [<ffffffff811e17e2>] do_readv_writev+0xe2/0x1e0
[ 8921.816702] [<ffffffff810b8dac>] ? do_setitimer+0x1ac/0x200
[ 8921.818819] [<ffffffff810e2ec1>] ? get_parent_ip+0x11/0x50
[ 8921.820863] [<ffffffff810e325e>] ? sub_preempt_count+0xae/0xf0
[ 8921.823318] [<ffffffff811e1926>] vfs_writev+0x46/0x60
[ 8921.825219] [<ffffffff811e1a3f>] sys_writev+0x4f/0xb0
[ 8921.827127] [<ffffffff82658039>] system_call_fastpath+0x16/0x1b
[ 8921.829384] ---[ end trace dffe390f30db9eb7 ]---

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Acked-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/phonet/pep.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index 2ba6e9f..007546d 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -1046,6 +1046,9 @@ static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,
int flags = msg->msg_flags;
int err, done;

+ if (len > USHRT_MAX)
+ return -EMSGSIZE;
+
if ((msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|
MSG_CMSG_COMPAT)) ||
!(msg->msg_flags & MSG_EOR))
--
1.7.10