Re: [edk2-devel] [PATCH] UefiPayloadPkg: CbParseLib: Fix integer overflow

["Sheng Lean Tan" <sheng.tan@9elements.com>]

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Hi Gua or Sean,
Would you mind to help review this?
Thanks!

Best Regards,
*Lean Sheng Tan*



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On Mon, 8 Jan 2024 at 08:00, Patrick Rudolph <patrick.rudolph@9elements.com>
wrote:

> The IMD entry uses the 32bit start field as relative offset
> to root. On Ia32X64 this works fine as UINTN is also 32 bit and
> negative relative offsets are properly calculated due to an
> integer overflow.
>
> On X64 this doesn't work as UINTN is 64 bit and the offset
> is no longer subtracted, but it's added to the root. Fix that
> by sign extending the start field to 64 bit.
>
> Test: Booting UefiPayloadPkg still works on Ia32X64 and now also
>       works on X64.
>
> Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
> ---
>  UefiPayloadPkg/Library/CbParseLib/CbParseLib.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/UefiPayloadPkg/Library/CbParseLib/CbParseLib.c
> b/UefiPayloadPkg/Library/CbParseLib/CbParseLib.c
> index 8a353f77f6..9e149532a7 100644
> --- a/UefiPayloadPkg/Library/CbParseLib/CbParseLib.c
> +++ b/UefiPayloadPkg/Library/CbParseLib/CbParseLib.c
> @@ -282,7 +282,7 @@ FindCbMemTable (
>    for (Idx = 0; Idx < Root->num_entries; Idx++) {
>      if (Entries[Idx].id == TableId) {
>        if (IsImdEntry) {
> -        *MemTable = (VOID *)((UINTN)Entries[Idx].start + (UINTN)Root);
> +        *MemTable = (VOID *)((INTN)(INT32)Entries[Idx].start +
> (UINTN)Root);
>        } else {
>          *MemTable = (VOID *)(UINTN)Entries[Idx].start;
>        }
> --
> 2.43.0
>
>


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