Re: [PATCH v2 1/1] MdePkg/BaseLib: Fix invalid memory access in AArch64 SetJump/LongJump

["Ard Biesheuvel" <ard.biesheuvel@arm.com>]

On 10/1/20 6:15 PM, Jan Bobek wrote:
> Correct the memory offsets used in REG_ONE/REG_PAIR macros to
> synchronize them with definition of the BASE_LIBRARY_JUMP_BUFFER
> structure on AArch64.
> 
> The REG_ONE macro declares only a single 64-bit register be
> read/written; however, the subsequent offset is 16 bytes larger,
> creating an unused memory gap in the middle of the structure and
> causing SetJump/LongJump functions to read/write 8 bytes of memory
> past the end of the jump buffer struct.
> 
> Signed-off-by: Jan Bobek <jbobek@nvidia.com>

Thanks Jan,

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

Liming, Michael: any concerns?

Thanks,


> ---
>   MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S   | 8 ++++----
>   MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm | 8 ++++----
>   2 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> index 72cea259e913..deefdf526b95 100644
> --- a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> +++ b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.S
> @@ -20,10 +20,10 @@ GCC_ASM_EXPORT(InternalLongJump)
>           REG_ONE  (x16,      96) /*IP0*/
>   
>   #define FPR_LAYOUT                      \
> -        REG_PAIR ( d8,  d9, 112);       \
> -        REG_PAIR (d10, d11, 128);       \
> -        REG_PAIR (d12, d13, 144);       \
> -        REG_PAIR (d14, d15, 160);
> +        REG_PAIR ( d8,  d9, 104);       \
> +        REG_PAIR (d10, d11, 120);       \
> +        REG_PAIR (d12, d13, 136);       \
> +        REG_PAIR (d14, d15, 152);
>   
>   #/**
>   #  Saves the current CPU context that can be restored with a call to LongJump() and returns 0.#
> diff --git a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> index 20dd0f1b850f..df70f298998e 100644
> --- a/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> +++ b/MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm
> @@ -19,10 +19,10 @@
>           REG_ONE  (x16,      #96) /*IP0*/
>   
>   #define FPR_LAYOUT                       \
> -        REG_PAIR ( d8,  d9, #112);       \
> -        REG_PAIR (d10, d11, #128);       \
> -        REG_PAIR (d12, d13, #144);       \
> -        REG_PAIR (d14, d15, #160);
> +        REG_PAIR ( d8,  d9, #104);       \
> +        REG_PAIR (d10, d11, #120);       \
> +        REG_PAIR (d12, d13, #136);       \
> +        REG_PAIR (d14, d15, #152);
>   
>   ;/**
>   ;  Saves the current CPU context that can be restored with a call to LongJump() and returns 0.#
>