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d141e72aef
In exfat, not only the newly allocated space will be mapped as
the new buffer, but also the space between ->valid_size and the
file size will be mapped as the new buffer. If the buffer is
mapped as new in ->write_begin(), it will be zeroed. But if the
buffer has been mapped as new before ->write_begin(), ->write_begin()
will not zero them, resulting in access to uninitialized data.
So this commit uses folio_zero_new_buffers() to zero the new buffers
after ->write_begin().
Fixes: 6630ea49103c ("exfat: move extend valid_size into ->page_mkwrite()")
Reported-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=91ae49e1c1a2634d20c0
Tested-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>