回复: [PATCH v3 1/1] MdePkg/BaseLib: Fix out-of-bounds reads in SafeString

["gaoliming" <gaoliming@byosoft.com.cn>]

Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

> -----邮件原件-----
> 发件人: Pedro Falcato <pedro.falcato@gmail.com>
> 发送时间: 2022年11月3日 9:12
> 收件人: devel@edk2.groups.io
> 抄送: Pedro Falcato <pedro.falcato@gmail.com>; Vitaly Cheptsov
> <vit9696@protonmail.com>; Marvin Häuser <mhaeuser@posteo.de>;
> Michael D Kinney <michael.d.kinney@intel.com>; Liming Gao
> <gaoliming@byosoft.com.cn>; Zhiguang Liu <zhiguang.liu@intel.com>; Jiewen
> Yao <Jiewen.yao@Intel.com>
> 主题: [PATCH v3 1/1] MdePkg/BaseLib: Fix out-of-bounds reads in SafeString
> 
> There was a OOB access in *StrHexTo* functions, when passed strings like
> "XDEADBEEF".
> 
> OpenCore folks established an ASAN-equipped project to fuzz Ext4Dxe,
> which was able to catch these (mostly harmless) issues.
> 
> Cc: Vitaly Cheptsov <vit9696@protonmail.com>
> Cc: Marvin Häuser <mhaeuser@posteo.de>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
> Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
> Reviewed-by: Jiewen Yao <Jiewen.yao@Intel.com>
> ---
>  MdePkg/Library/BaseLib/SafeString.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/MdePkg/Library/BaseLib/SafeString.c
> b/MdePkg/Library/BaseLib/SafeString.c
> index f338a32a3a41..b75b33381732 100644
> --- a/MdePkg/Library/BaseLib/SafeString.c
> +++ b/MdePkg/Library/BaseLib/SafeString.c
> @@ -863,6 +863,9 @@ StrHexToUintnS (
>    OUT       UINTN   *Data
>    )
>  {
> +  BOOLEAN  FoundLeadingZero;
> +
> +  FoundLeadingZero = FALSE;
>    ASSERT (((UINTN)String & BIT0) == 0);
> 
>    //
> @@ -892,12 +895,14 @@ StrHexToUintnS (
>    //
>    // Ignore leading Zeros after the spaces
>    //
> +
> +  FoundLeadingZero = *String == L'0';
>    while (*String == L'0') {
>      String++;
>    }
> 
>    if (CharToUpper (*String) == L'X') {
> -    if (*(String - 1) != L'0') {
> +    if (!FoundLeadingZero) {
>        *Data = 0;
>        return RETURN_SUCCESS;
>      }
> @@ -992,6 +997,9 @@ StrHexToUint64S (
>    OUT       UINT64  *Data
>    )
>  {
> +  BOOLEAN  FoundLeadingZero;
> +
> +  FoundLeadingZero = FALSE;
>    ASSERT (((UINTN)String & BIT0) == 0);
> 
>    //
> @@ -1021,12 +1029,13 @@ StrHexToUint64S (
>    //
>    // Ignore leading Zeros after the spaces
>    //
> +  FoundLeadingZero = *String == L'0';
>    while (*String == L'0') {
>      String++;
>    }
> 
>    if (CharToUpper (*String) == L'X') {
> -    if (*(String - 1) != L'0') {
> +    if (!FoundLeadingZero) {
>        *Data = 0;
>        return RETURN_SUCCESS;
>      }
> @@ -2393,6 +2402,9 @@ AsciiStrHexToUintnS (
>    OUT       UINTN  *Data
>    )
>  {
> +  BOOLEAN  FoundLeadingZero;
> +
> +  FoundLeadingZero = FALSE;
>    //
>    // 1. Neither String nor Data shall be a null pointer.
>    //
> @@ -2420,12 +2432,13 @@ AsciiStrHexToUintnS (
>    //
>    // Ignore leading Zeros after the spaces
>    //
> +  FoundLeadingZero = *String == '0';
>    while (*String == '0') {
>      String++;
>    }
> 
>    if (AsciiCharToUpper (*String) == 'X') {
> -    if (*(String - 1) != '0') {
> +    if (!FoundLeadingZero) {
>        *Data = 0;
>        return RETURN_SUCCESS;
>      }
> @@ -2517,6 +2530,9 @@ AsciiStrHexToUint64S (
>    OUT       UINT64  *Data
>    )
>  {
> +  BOOLEAN  FoundLeadingZero;
> +
> +  FoundLeadingZero = FALSE;
>    //
>    // 1. Neither String nor Data shall be a null pointer.
>    //
> @@ -2544,12 +2560,13 @@ AsciiStrHexToUint64S (
>    //
>    // Ignore leading Zeros after the spaces
>    //
> +  FoundLeadingZero = *String == '0';
>    while (*String == '0') {
>      String++;
>    }
> 
>    if (AsciiCharToUpper (*String) == 'X') {
> -    if (*(String - 1) != '0') {
> +    if (!FoundLeadingZero) {
>        *Data = 0;
>        return RETURN_SUCCESS;
>      }
> --
> 2.38.1