Commit 2842e873 authored by Jonathan Salwan's avatar Jonathan Salwan Committed by Greg Kroah-Hartman

drivers/cdrom/cdrom.c: use kzalloc() for failing hardware

commit 542db01579fbb7ea7d1f7bb9ddcef1559df660b2 upstream.

In drivers/cdrom/cdrom.c mmc_ioctl_cdrom_read_data() allocates a memory
area with kmalloc in line 2885.

  2885         cgc->buffer = kmalloc(blocksize, GFP_KERNEL);
  2886         if (cgc->buffer == NULL)
  2887                 return -ENOMEM;

In line 2908 we can find the copy_to_user function:

  2908         if (!ret && copy_to_user(arg, cgc->buffer, blocksize))

The cgc->buffer is never cleaned and initialized before this function.
If ret = 0 with the previous basic block, it's possible to display some
memory bytes in kernel space from userspace.

When we read a block from the disk it normally fills the ->buffer but if
the drive is malfunctioning there is a chance that it would only be
partially filled.  The result is an leak information to userspace.
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Jonathan Salwan <jonathan.salwan@gmail.com>
Cc: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1b7927f0
......@@ -2882,7 +2882,7 @@ static noinline int mmc_ioctl_cdrom_read_data(struct cdrom_device_info *cdi,
if (lba < 0)
return -EINVAL;
cgc->buffer = kmalloc(blocksize, GFP_KERNEL);
cgc->buffer = kzalloc(blocksize, GFP_KERNEL);
if (cgc->buffer == NULL)
return -ENOMEM;
......
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