4.9-stable review patch. If anyone has any objections, please let me know.
------------------
[ 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 --- fs/pstore/platform.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -584,8 +584,8 @@ static void pstore_console_write(struct } 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;