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

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The intention of commit aae8679b0ebcaa92f99c1c3cb0cd651594a43915
("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>
This commit is contained in:
Vitaly Mayatskikh 2009-04-30 15:08:18 -07:00 committed by Linus Torvalds
parent b827e496c8
commit 0816178638
1 changed files with 4 additions and 0 deletions
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4
fs/proc/task_mmu.c
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@ -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;