Messages in this thread | | | Date | Thu, 7 Sep 2017 17:05:19 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH 06/14] md/bcache: Use %pS printk format for direct addresses |
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On (09/07/17 09:42), Helge Deller wrote: > >> - seq_printf(f, "%p: %pF -> %pf p %p r %i ", > >> + seq_printf(f, "%p: %pS -> %pf p %p r %i ", > >> cl, (void *) cl->ip, cl->fn, cl->parent, > >> r & CLOSURE_REMAINING_MASK); > >> > >> @@ -187,7 +187,7 @@ static int debug_seq_show(struct seq_file *f, void *data) > >> r & CLOSURE_SLEEPING ? "Sl" : ""); > >> > >> if (r & CLOSURE_WAITING) > >> - seq_printf(f, " W %pF\n", > >> + seq_printf(f, " W %pS\n", > >> (void *) cl->waiting_on); > >> > >> seq_printf(f, "\n"); > >> > > > > It is unclear to me, that if %pF is used, on ia64/ppc64/parisc64 a > > function descriptor conversion happens, what negative effect exactly > > takes place ? > > On ia64/ppc64/parisc64 the kernel will crash here in the worst case, because > vsprintf() will try to read a pointer from that address and resolve it.
probe_kernel_address() handles the page fault and returns -EFAULT if you give it bad pointer. module_address_lookup() and get_symbol_pos() seems to be smart enough not to crash on bad pointer as well. what am I missing? could you please explain where we will crash?
-ss
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