[patch] x86/crash: fix crash_setup_memmap_entries() out-of-bounds access

[Borislav Petkov]

On Fri, Apr 16, 2021 at 02:02:07PM +0200, Mike Galbraith wrote:
> [   15.428011] BUG: KASAN: vmalloc-out-of-bounds in crash_setup_memmap_entries+0x17e/0x3a0
> [   15.428018] Write of size 8 at addr ffffc90000426008 by task kexec/1187
> 
> (gdb) list *crash_setup_memmap_entries+0x17e
> 0xffffffff8107cafe is in crash_setup_memmap_entries (arch/x86/kernel/crash.c:322).
> 317                                      unsigned long long mend)
> 318     {
> 319             unsigned long start, end;
> 320
> 321             cmem->ranges[0].start = mstart;
> 322             cmem->ranges[0].end = mend;
> 323             cmem->nr_ranges = 1;
> 324
> 325             /* Exclude elf header region */
> 326             start = image->arch.elf_load_addr;
> (gdb)
> 
> Append missing struct crash_mem_range to cmem.

This is winning this year's contest for most laconic patch commit
message! :-)

Please be more verbose and structure your commit message like this:

Problem is A.

It happens because of B.

Fix it by doing C.

(Potentially do D).

For more detailed info, see
Documentation/process/submitting-patches.rst, Section "2) Describe your
changes".

Thx.

-- 
Regards/Gruss,
    Boris.

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