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

The intention of commit aae8679b0e
("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 <[email protected]>
Cc: Thomas Tuttle <[email protected]>
Acked-by: Matt Mackall <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Vitaly Mayatskikh 2009-04-30 15:08:18 -07:00 • committed by Linus Torvalds
commit 0816178638

View file

@ -665,6 +665,10 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
goto out_task;
ret = 0;
if (!count)
goto out_task;
mm = get_task_mm(task);
if (!mm)
goto out_task;