[patch 34/56] seq_file: fix big-enough lseek() + read()

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.
------------------

From: Alexey Dobriyan <adobriyan@xxxxxxxxx>

commit f01d1d546abb2f4028b5299092f529eefb01253a upstream.

lseek() further than length of the file will leave stale ->index
(second-to-last during iteration). Next seq_read() will not notice
that ->f_pos is big enough to return 0, but will print last item
as if ->f_pos is pointing to it.

Introduced in commit cb510b8172602a66467f3551b4be1911f5a7c8c2
aka "seq_file: more atomicity in traverse()".

Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/seq_file.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -102,6 +102,7 @@ static int traverse(struct seq_file *m, 
 		p = m->op->next(m, p, &index);
 	}
 	m->op->stop(m, p);
+	m->index = index;
 	return error;
 
 Eoverflow:

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