Re: [PATCH] fix: general protection fault in iter_file_splice_write
From: Jan Kara
Date: Mon Nov 04 2024 - 07:06:29 EST
On Mon 04-11-24 00:42:39, Daniel Yang wrote:
> The function iter_file_splice_write() calls pipe_buf_release() which has
> a nullptr dereference in ops->release. Add check for buf->ops not null
> before calling pipe_buf_release().
>
> Signed-off-by: Daniel Yang <danielyangkang@xxxxxxxxx>
> Reported-by: syzbot+d2125fcb6aa8c4276fd2@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=d2125fcb6aa8c4276fd2
> Fixes: 2df86547b23d ("netfs: Cut over to using new writeback code")
> ---
> fs/splice.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/splice.c b/fs/splice.c
> index 06232d7e5..b8c503e47 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -756,7 +756,8 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
> if (ret >= buf->len) {
> ret -= buf->len;
> buf->len = 0;
> - pipe_buf_release(pipe, buf);
> + if (buf->ops)
> + pipe_buf_release(pipe, buf);
Umm, already released pipe buf? How would it get here? We have filled the
buffers shortly before so IMHO it indicates some deeper problem. Can you
please explain a bit more?
Honza
> tail++;
> pipe->tail = tail;
> if (pipe->files)
> --
> 2.39.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR