Messages in this thread | | | Date | Mon, 5 Mar 2018 15:53:06 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH] vsprintf: Make "null" pointer dereference more robust |
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On Fri 2018-03-02 16:17:34, Andy Shevchenko wrote: > On Fri, 2018-03-02 at 13:53 +0100, Petr Mladek wrote: > > %p has many modifiers where the pointer is dereferenced. An invalid > > pointer might cause kernel to crash silently. > > > > Note that printk() formats the string under logbuf_lock. Any recursive > > printks are redirected to the printk_safe implementation and the > > messages > > are stored into per-CPU buffers. These buffers might be eventually > > flushed > > in printk_safe_flush_on_panic() but it is not guaranteed. > > > > In general, we should do our best to get useful message from printk(). > > All pointers to the first memory page must be invalid. Let's prevent > > the dereference and print "(null)" in this case. This is already done > > in many other situations, including "%s" format handling and many > > page fault handlers. > > > > > With such explanation it makes at least clear for the reader why it's > done. > > Thanks! > > Would you be okay if I take this one as a first in my series and > resubmit the series based on it?
Makes sense. Feel free to go on.
Best Regards, Petr
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