• Jonathan Salwan's avatar
    drivers/cdrom/cdrom.c: use kzalloc() for failing hardware · 2842e873
    Jonathan Salwan authored
    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: 's avatarDan Carpenter <dan.carpenter@oracle.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    Cc: Jonathan Salwan <jonathan.salwan@gmail.com>
    Cc: Luis Henriques <luis.henriques@canonical.com>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    2842e873
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