seq_file: always clear m->count when we free m->buf

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>

diff --git a/fs/seq_file.c b/fs/seq_file.c
index a290157265ef5cfb52dbdb6a9e950e9733462d16..092951efaf4395816dda3432cba06e4368f15075 100644 (file)
--- 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);