Hi Mike,
Thanks for the patch! I suggest always cc kexec list for kexec/kdump
patches.
On 04/15/21 at 07:56pm, Mike Galbraith wrote:
> x86/crash: fix crash_setup_memmap_entries() KASAN vmalloc-out-of-bounds gripe
>
> [ 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)
>
> We're excluding two ranges, allocate the scratch space we need to do that.
I think 1 range should be fine, have you tested 1?
The code is just excluding the elf header space which will be loaded
first before anything else so I assume it will be just at the start of
the crashkernel resource region. Thus [a b] after exclude the start
part will be [c b]. But I have not read the code for long time, maybe I
need to double check.
But anyway 2 would be good since the code is obscure we can easily miss
it in the future. See how other people think.
>
> Signed-off-by: Mike Galbraith <efault@xxxxxx>
> ---
> arch/x86/kernel/crash.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -337,7 +337,7 @@ int crash_setup_memmap_entries(struct ki
> struct crash_memmap_data cmd;
> struct crash_mem *cmem;
>
> - cmem = vzalloc(sizeof(struct crash_mem));
> + cmem = vzalloc(sizeof(struct crash_mem)+(2*sizeof(struct crash_mem_range)));
Thanks for the patch, can you try below?
vzalloc(struct_size(cmem, ranges, 2));
> if (!cmem)
> return -ENOMEM;
>
>
Thanks
Dave
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