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staging: comedi: comedi_fops: do not call blocking ops when !TASK_RUNNING

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commit cef988642cdac44e910a27cb6e8166c96f86a0df upstream.

Comedi's read and write file operation handlers (`comedi_read()` and
`comedi_write()`) currently call `copy_to_user()` or `copy_from_user()`
whilst in the `TASK_INTERRUPTIBLE` state, which falls foul of the
`might_fault()` checks when enabled.  Fix it by setting the current task
state back to `TASK_RUNNING` a bit earlier before calling these
functions.

Reported-by: Piotr Gregor <piotrgregor@rsyncme.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2017-07-28 16:22:31 +01:00 committed by Greg Kroah-Hartman
parent bbae08213e
commit b189f8eb27
1 changed files with 3 additions and 0 deletions
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3
drivers/staging/comedi/comedi_fops.c
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@ -2385,6 +2385,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
continue;
}
set_current_state(TASK_RUNNING);
wp = async->buf_write_ptr;
n1 = min(n, async->prealloc_bufsz - wp);
n2 = n - n1;
@ -2517,6 +2518,8 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
}
continue;
}
set_current_state(TASK_RUNNING);
rp = async->buf_read_ptr;
n1 = min(n, async->prealloc_bufsz - rp);
n2 = n - n1;