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Subject[PATCH v2] tty: rocket: Fix a kernel address leak in rp_ioctl
Date
If the cmd is RCPK_GET_STRUCT, copy_to_user will copy
info to user space. As info->port.ops is the address of
a constant object rocket_port_ops (assigned in init_r_port),
a kernel address leakage happens.

This patch sets all the pointer fields to NULL before copy the
object to user space to avoid kernel address leakage.

Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
---
drivers/tty/rocket.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/rocket.c b/drivers/tty/rocket.c
index b121d8f8f3d7..a7bcf44b61bd 100644
--- a/drivers/tty/rocket.c
+++ b/drivers/tty/rocket.c
@@ -1271,6 +1271,34 @@ static int get_version(struct r_port *info, struct rocket_version __user *retver
return 0;
}

+static int get_struct(struct r_port *info, void *argp)
+{
+ struct r_port *new;
+ int ret = 0;
+
+ new = kzalloc(sizeof (struct r_port), GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+ memcpy(new, info, sizeof (struct r_port));
+ new->port.tty = NULL;
+ new->port.itty = NULL;
+ new->port.ops = NULL;
+ new->port.client_ops = NULL;
+ memset(&new->port.open_wait.head, 0, sizeof (struct list_head));
+ memset(&new->port.delta_msr_wait.head, 0, sizeof (struct list_head));
+ memset(&new->port.mutex.wait_list, 0, sizeof (struct list_head));
+ memset(&new->port.buf_mutex.wait_list, 0, sizeof (struct list_head));
+ new->port.xmit_buf = NULL;
+ new->port.client_data = NULL;
+ new->ctlp = NULL;
+ new->xmit_buf = NULL;
+ memset(&new->write_mtx.wait_list, 0, sizeof (struct list_head));
+ if (copy_to_user(argp, new, sizeof (struct r_port)))
+ ret = -EFAULT;
+ kfree(new);
+ return ret;
+}
+
/* IOCTL call handler into the driver */
static int rp_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
@@ -1284,8 +1312,7 @@ static int rp_ioctl(struct tty_struct *tty,

switch (cmd) {
case RCKP_GET_STRUCT:
- if (copy_to_user(argp, info, sizeof (struct r_port)))
- ret = -EFAULT;
+ ret = get_struct(info, argp);
break;
case RCKP_GET_CONFIG:
ret = get_config(info, argp);
--
2.11.0
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