pstore: Convert console write to use ->write_buf

[ Upstream commit 70ad35db3321a6d129245979de4ac9d06eed897c ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 43033a3d66d5ea5dedeb95b2f44f5b3f9679b3a6..2434bffbc6ddd5cc645258ed842fbb94c983ab36 100644 (file)
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -584,8 +584,8 @@ 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;