pstore: Convert console write to use ->write_buf

Maybe I'm missing something, but I don't know why it needs to copy the
input buffer to psinfo->buf and then write.  Instead we can write the
input buffer directly.  The only implementation that supports console
message (i.e. ramoops) already does it for ftrace messages.

For the upcoming virtio backend driver, it needs to protect psinfo->buf
overwritten from console messages.  If it could use ->write_buf method
instead of ->write, the problem will be solved easily.

Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 60e6db6f5da2bfe7f8ea785504713442bedccf8e..729677e18e364fbff1d66e89fb93450d592f55e8 100644 (file)
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -585,8 +585,8 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
                } else {
                        spin_lock_irqsave(&psinfo->buf_lock, flags);
                }
-               memcpy(psinfo->buf, s, c);
-               psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
+               psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
+                                 s, 0, c, psinfo);
                spin_unlock_irqrestore(&psinfo->buf_lock, flags);
                s += c;
                c = e - s;