Messages in this thread |  | | Subject | Re: [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference | From | Mike Galbraith <> | Date | Thu, 09 Aug 2018 09:33:30 +0200 |
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On Thu, 2018-08-09 at 12:21 +0800, Dave Young wrote: > Hi Mike, > > Thanks for the patch! > On 08/08/18 at 04:03pm, Mike Galbraith wrote: > > When booting with efi=noruntime, we call efi_runtime_map_copy() while > > loading the kdump kernel, and trip over a NULL efi.memmap.map. Avoid > > that and a useless allocation when the only mapping we can use (1:1) > > is not available. > > At first glance, efi_get_runtime_map_size should return 0 in case > noruntime.
What efi does internally at unmap time is to leave everything except efi.mmap.map untouched, setting it to NULL and turning off EFI_MEMMAP, rendering efi.mmap.map accessors useless/unsafe without first checking EFI_MEMMAP.
-Mike
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