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Subject[095/127] HID: hidraw, fix a NULL pointer dereference in hidraw_write
2.6.32-stable review patch.  If anyone has any objections, please let us know.

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

From: Antonio Ospite <ospite@studenti.unina.it>

commit e42dee9a99a3ecd32b5c027e8f7411fb5bc11eb6 upstream.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa0f0a625>] hidraw_write+0x3b/0x116 [hid]
[...]

This is reproducible by disconnecting the device while userspace writes
to dev node in a loop and doesn't check return values in order to exit
the loop.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/hid/hidraw.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -105,11 +105,15 @@ out:
static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
unsigned int minor = iminor(file->f_path.dentry->d_inode);
- /* FIXME: What stops hidraw_table going NULL */
- struct hid_device *dev = hidraw_table[minor]->hid;
+ struct hid_device *dev;
__u8 *buf;
int ret = 0;

+ if (!hidraw_table[minor])
+ return -ENODEV;
+
+ dev = hidraw_table[minor]->hid;
+
if (!dev->hid_output_raw_report)
return -ENODEV;




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