Commit 14be2746 authored Sep 18, 2009 by Steven Rostedt Committed by Al Viro Sep 24, 2009

libfs: make simple_read_from_buffer conventional



Impact: have simple_read_from_buffer conform to standards

It was brought to my attention by Andrew Morton, Theodore Tso, and H.
Peter Anvin that a read from userspace should only return -EFAULT if
nothing was actually read.

Looking at the simple_read_from_buffer I noticed that this function does
not conform to that rule.  This patch fixes that function.

[akpm@linux-foundation.org: simplification suggested by hpa]
[hpa@zytor.com: fix count==0 handling]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 94a8d5ca

fs/libfs.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -527,14 +527,18 @@ ssize_t simple_read_from_buffer(void __user to, size_t count, loff_t ppos,
		const void *from, size_t available)
		{
		loff_t pos = *ppos;
		size_t ret;

		if (pos < 0)
		return -EINVAL;
		if (pos >= available)
		if (pos >= available \|\| !count)
		return 0;
		if (count > available - pos)
		count = available - pos;
		if (copy_to_user(to, from + pos, count))
		ret = copy_to_user(to, from + pos, count);
		if (ret == count)
		return -EFAULT;
		count -= ret;
		*ppos = pos + count;
		return count;
		}

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