From: Alexey Dobriyan <adobriyan@gmail.com>
Date: Thu, 5 Feb 2009 21:30:05 +0000 (+0300)
Subject: seq_file: fix big-enough lseek() + read()
X-Git-Tag: v2.6.27.16~23
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=de6470415bc59d9d5736799c0803c6103b7d86b9;p=thirdparty%2Fkernel%2Fstable.git

seq_file: fix big-enough lseek() + read()

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@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 704e5a8e6647d..ef4d4970a7d08 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -102,6 +102,7 @@ static int traverse(struct seq_file *m, loff_t offset)
 		p = m->op->next(m, p, &index);
 	}
 	m->op->stop(m, p);
+	m->index = index;
 	return error;
 
 Eoverflow: