Commit 08161786 authored Apr 30, 2009 by Vitaly Mayatskikh Committed by Linus Torvalds May 02, 2009

pagemap: require aligned-length, non-null reads of /proc/pid/pagemap



The intention of commit aae8679b
("pagemap: fix bug in add_to_pagemap, require aligned-length reads of
/proc/pid/pagemap") was to force reads of /proc/pid/pagemap to be a
multiple of 8 bytes, but now it allows to read 0 bytes, which actually
puts some data to user's buffer.  According to POSIX, if count is zero,
read() should return zero and has no other results.

Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Cc: Thomas Tuttle <ttuttle@google.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent b827e496

fs/proc/task_mmu.c

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -665,6 +665,10 @@ static ssize_t pagemap_read(struct file file, char __user buf,
	goto out_task;		goto out_task;

	ret = 0;		ret = 0;

			if (!count)
			goto out_task;

	mm = get_task_mm(task);		mm = get_task_mm(task);
	if (!mm)		if (!mm)
	goto out_task;		goto out_task;