On 11/28, Oleg Nesterov wrote: > > On top of this series, not for inclusion yet, just to explain what > I mean. May be someone can test it ;) > > This series kills xol_vma. Instead we use the per_cpu-like xol slots. > > This is much more simple and efficient. And this of course solves > many problems we currently have with xol_vma. > > For example, we simply can not trust it. We do not know what actually > we are going to execute in UTASK_SSTEP mode. An application can unmap > this area and then do mmap(PROT_EXEC|PROT_WRITE, MAP_FIXED) to fool > uprobes. > > The only disadvantage is that this adds a bit more arch-dependant > code. > > The main question, can this work? OK, it almost works. But, this way we can't probe the compat tasks. A __USER32_CS task can't access the fix_to_virt() area, so it can't use uprobe_xol_slots[]. Many thanks to Josh who noticed this. I'll try to think more, but so far I do not see any simple solution. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>