Linus Torvalds 48466c4772 vfs,mm: fix return value of read() at s_maxbytes
commit d05c5f7ba164aed3db02fb188c26d0dd94f5455b upstream.

We truncated the possible read iterator to s_maxbytes in commit
c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()"),
but our end condition handling was wrong: it's not an error to try to
read at the end of the file.

Reading past the end should return EOF (0), not EINVAL.

See for example

  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1649342
  http://lists.gnu.org/archive/html/bug-coreutils/2016-12/msg00008.html

where a md5sum of a maximally sized file fails because the final read is
exactly at s_maxbytes.

Fixes: c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()")
Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Cc: Wei Fang <fangwei1@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-06 10:40:13 +01:00
..
2016-10-24 19:13:20 -07:00
2015-09-08 15:35:28 -07:00
2016-03-17 15:09:34 -07:00
2015-11-05 19:34:48 -08:00
2016-10-24 19:13:20 -07:00
2016-03-17 15:09:34 -07:00
2016-09-06 18:30:20 +02:00
2016-10-07 18:46:27 -07:00