Re: [PATCH] vsprintf: Do not break early boot with probing addresses
From: Petr Mladek <pmladek@suse.com>
Date: 2019-05-10 14:49:21
Also in:
linux-arch, linux-s390, lkml
On Fri 2019-05-10 10:42:13, Petr Mladek wrote:
The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
invalid pointers") broke boot on several architectures. The common
pattern is that probe_kernel_read() is not working during early
boot because userspace access framework is not ready.
It is a generic problem. We have to avoid any complex external
functions in vsprintf() code, especially in the common path.
They might break printk() easily and are hard to debug.
Replace probe_kernel_read() with some simple checks for obvious
problems.JFYI, I have sent a pull request with this patch, see https://lkml.kernel.org/r/20190510144718.riyy72g4cy5nkggx@pathway.suse.cz Best Regards, Petr