(2014/11/24 20:13), Thomas Gleixner wrote: > On Thu, 20 Nov 2014, Seth Jennings wrote: >> This commit introduces code for the live patching core. It implements >> an ftrace-based mechanism and kernel interface for doing live patching >> of kernel and kernel module functions. >> >> It represents the greatest common functionality set between kpatch and >> kgraft and can accept patches built using either method. >> >> This first version does not implement any consistency mechanism that >> ensures that old and new code do not run together. In practice, ~90% of >> CVEs are safe to apply in this way, since they simply add a conditional >> check. However, any function change that can not execute safely with >> the old version of the function can _not_ be safely applied in this >> version. > > To be honest this sounds frightening. > I see. This is just a minimal one. We'll add several consistency mechanisms :). > How is determined whether a change can be applied w/o a consistency > mechanism or not? I guess the following cases are possible to be applied. - the code itself ensures consistency (e.g. in a critical section) or, - the patch just changes one place (e.g. add an if branch) and only depends on the local context (e.g. local variables), and doesn't called in a loop, so that old- and new-version of the function can co-exist. Thank you, > > Thanks, > > tglx > > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@xxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
