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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Vasily Averin <vvs@virtuozzo.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Oberparleiter <oberpar@linux.ibm.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Ingo Molnar <mingo@redhat.com>,
        Manfred Spraul <manfred@colorfullife.com>,
        NeilBrown <neilb@suse.com>, Steven Rostedt <rostedt@goodmis.org>,
        Waiman Long <longman@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 14/80] kernel/gcov/fs.c: gcov_seq_next() should increase position index
Date:   Fri,  1 May 2020 15:21:08 +0200
Message-Id: <20200501131518.274814134@linuxfoundation.org>
In-Reply-To: <20200501131513.810761598@linuxfoundation.org>
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From: Vasily Averin <vvs@virtuozzo.com>

[ Upstream commit f4d74ef6220c1eda0875da30457bef5c7111ab06 ]

If seq_file .next function does not change position index, read after
some lseek can generate unexpected output.

https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: NeilBrown <neilb@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Waiman Long <longman@redhat.com>
Link: http://lkml.kernel.org/r/f65c6ee7-bd00-f910-2f8a-37cc67e4ff88@virtuozzo.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/gcov/fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/gcov/fs.c b/kernel/gcov/fs.c
index edf67c493a8e1..e473f6a1f6ca7 100644
--- a/kernel/gcov/fs.c
+++ b/kernel/gcov/fs.c
@@ -108,9 +108,9 @@ static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
 {
 	struct gcov_iterator *iter = data;
 
+	(*pos)++;
 	if (gcov_iter_next(iter))
 		return NULL;
-	(*pos)++;
 
 	return iter;
 }
-- 
2.20.1