[PATCH 10/15] acpi: ec_sys: access user space with get_user()/put_user()

[Jiri Slaby]

From: Vasiliy Kulikov <sego...@gmail.com>

User space pointer may not be dereferenced. Use get_user()/put_user()
instead and check their return codes.

Signed-off-by: Vasiliy Kulikov <sego...@gmail.com>
Signed-off-by: Thomas Renninger <tr...@suse.de>
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
Cc: Len Brown <l...@kernel.org>
Cc: "Rafael J. Wysocki" <r...@sisk.pl>
Cc: linux-a...@vger.kernel.org
---
 drivers/acpi/ec_sys.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c
index 7586544..4e7b798 100644
--- a/drivers/acpi/ec_sys.c
+++ b/drivers/acpi/ec_sys.c
@@ -12,6 +12,7 @@
 #include <linux/acpi.h>
 #include <linux/debugfs.h>
 #include <linux/module.h>
+#include <linux/uaccess.h>
 #include "internal.h"
 
 MODULE_AUTHOR("Thomas Renninger <tr...@suse.de>");
@@ -34,7 +35,6 @@ static ssize_t acpi_ec_read_io(struct file *f, char __user 
*buf,
         * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
         */
        unsigned int size = EC_SPACE_SIZE;
-       u8 *data = (u8 *) buf;
        loff_t init_off = *off;
        int err = 0;
 
@@ -47,9 +47,15 @@ static ssize_t acpi_ec_read_io(struct file *f, char __user 
*buf,
                size = count;
 
        while (size) {
-               err = ec_read(*off, &data[*off - init_off]);
+               u8 byte_read;
+               err = ec_read(*off, &byte_read);
                if (err)
                        return err;
+               if (put_user(byte_read, buf + *off - init_off)) {
+                       if (*off - init_off)
+                               return *off - init_off; /* partial read */
+                       return -EFAULT;
+               }
                *off += 1;
                size--;
        }
@@ -65,7 +71,6 @@ static ssize_t acpi_ec_write_io(struct file *f, const char 
__user *buf,
 
        unsigned int size = count;
        loff_t init_off = *off;
-       u8 *data = (u8 *) buf;
        int err = 0;
 
        if (*off >= EC_SPACE_SIZE)
@@ -76,7 +81,12 @@ static ssize_t acpi_ec_write_io(struct file *f, const char 
__user *buf,
        }
 
        while (size) {
-               u8 byte_write = data[*off - init_off];
+               u8 byte_write;
+               if (get_user(byte_write, buf + *off - init_off)) {
+                       if (*off - init_off)
+                               return *off - init_off; /* partial write */
+                       return -EFAULT;
+               }
                err = ec_write(*off, byte_write);
                if (err)
                        return err;
-- 
1.8.2.1

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