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mei: revamp read and write length checks 

1. Return zero on zero length read and writes
2. For a too large write return -EFBIG as defined in man write(2)
EFBIG  An attempt was made to write a file that
        exceeds the implementation-defined maximum
        file size or the process's file size limit,
        or to  write  at  a  position  past  the  maximum
        allowed offset.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tomas Winkler 2013-09-02 03:11:04 +03:00 committed by Greg Kroah-Hartman
parent e19555ce89
commit dd5de1f165
1 changed files with 14 additions and 2 deletions
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16
drivers/misc/mei/main.c
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@ -203,12 +203,18 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
dev = cl->dev;
mutex_lock(&dev->device_lock);
if (dev->dev_state != MEI_DEV_ENABLED) {
rets = -ENODEV;
goto out;
}
if (length == 0) {
rets = 0;
goto out;
}
if (cl == &dev->iamthif_cl) {
rets = mei_amthif_read(dev, file, ubuf, length, offset);
goto out;
@ -350,8 +356,14 @@ static ssize_t mei_write(struct file *file, const char __user *ubuf,
rets = -ENODEV;
goto out;
}
if (length > dev->me_clients[id].props.max_msg_length || length <= 0) {
rets = -EMSGSIZE;
if (length == 0) {
rets = 0;
goto out;
}
if (length > dev->me_clients[id].props.max_msg_length) {
rets = -EFBIG;
goto out;
}