]> err.no Git - linux-2.6/commit
sysfs: fix off-by-one error in fill_read_buffer()
authorMiao Xie <miaox@cn.fujitsu.com>
Wed, 21 Nov 2007 22:55:19 +0000 (14:55 -0800)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 28 Nov 2007 21:53:53 +0000 (13:53 -0800)
commit8118a859dc7abd873193986c77a8d9bdb877adc8
tree6b66719637ba2b4174c126cb751a090de0536269
parent71409a498e96a421bdc20e7275ebc4fab8b14cdc
sysfs: fix off-by-one error in fill_read_buffer()

I found that there is a off-by-one problem in the following code.

Version: 2.6.24-rc2
File: fs/sysfs/file.c:118-122
Function: fill_read_buffer
--------------------------------------------------------------------
count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);

sysfs_put_active_two(attr_sd);

BUG_ON(count > (ssize_t)PAGE_SIZE);
--------------------------------------------------------------------

Because according to the specification of the sysfs and the implement of
the show methods, the show methods return the number of bytes which would
be generated for the given input, excluding the trailing null.So if the
return value of the show methods equals PAGE_SIZE - 1, the buffer is full
in fact.  And if the return value equals PAGE_SIZE, the resulting string
was already truncated,or buffer overflow occurred.

This patch fixes an off-by-one error in fill_read_buffer.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tejun Heo <teheo@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
fs/sysfs/file.c