On 10/14/2014 09:28 AM, Martin Kelly wrote: > On Tue, Oct 14, 2014 at 9:09 AM, David Vrabel <david.vra...@citrix.com> wrote: >> On 14/10/14 15:04, Martin Kelly wrote: >>> On 10/14/2014 02:22 AM, David Vrabel wrote: >>>> On 14/10/14 02:19, Martin Kelly wrote: >>>>> In a call to set_phys_range_identity, i-1 is used without checking that >>>>> i is non-zero. Although unlikely, a bug in the code before it could >>>>> cause the value to be 0, leading to erroneous behavior. This patch adds >>>>> a check against 0 value and a corresponding warning. >>>> >>>> This can only happen if the toolstack supplies a memory map with zero >>>> entries. I could see justification for adding a panic at the top of >>>> this function in this case, but I can't see the usefulness of this warning. >>>> >>> >>> Yes, a panic is probably appropriate. What do you think about the >>> relative merits of panicing in the callers vs. in the >>> sanitize_e820_map function itself (thus to avoid a bunch of similar >>> error checks in the callers)? >> >> For Xen, it should panic immediately after getting the memory map. >> >> You will note that there is fallback code for the case when no memory >> map is provided. But I do not think this should be used in the case >> where the toolstack provided an empty memory map. >> >> David > > Sounds like the flow should be as follows: > 1) Ask Xen for the memory map. > 2) If no memory map is provided, use fallback code. > 3) If the memory map has 0 entries, panic. > > I will revise the patch to do that. >
I have sent a revision adding the panic: "[PATCH] x86/xen: panic on bad Xen-provided memory map" -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
