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

Jiri Slaby
2015-05-16T08:07:13Z

From: Al Viro <viro@ZenIV.linux.org.uk>

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@broadcom.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
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