[PATCH 3.12 107/142] seq_file: always clear m->count when we free m->buf

[Jiri Slaby]

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 801a76050bcf8d4e500eb8d048ff6265f37a61c8 upstream.

Once we'd freed m->buf, m->count should become zero - we have no valid
contents reachable via m->buf.

Reported-by: Charley (Hao Chuan) Chu <charley.chu@xxxxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 fs/seq_file.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index a290157265ef..092951efaf43 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -136,6 +136,7 @@ static int traverse(struct seq_file *m, loff_t offset)
 Eoverflow:
 	m->op->stop(m, p);
 	kfree(m->buf);
+	m->count = 0;
 	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
 	return !m->buf ? -ENOMEM : -EAGAIN;
 }
@@ -232,10 +233,10 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 			goto Fill;
 		m->op->stop(m, p);
 		kfree(m->buf);
+		m->count = 0;
 		m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
 		if (!m->buf)
 			goto Enomem;
-		m->count = 0;
 		m->version = 0;
 		pos = m->index;
 		p = m->op->start(m, &pos);
-- 
2.3.7

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