[edk2-devel] [PATCH] CryptoPkg/BaseCryptLib: fix NULL dereference (CVE-2019-14584)

[Yao, Jiewen]

Reviewed-by: Jiewen Yao <Jiewen.yao at intel.com>

> -----Original Message-----
> From: Wang, Jian J <jian.j.wang at intel.com>
> Sent: Friday, October 16, 2020 1:15 PM
> To: devel at edk2.groups.io
> Cc: Lu, XiaoyuX <xiaoyux.lu at intel.com>; Jiang, Guomin
> <guomin.jiang at intel.com>; Yao, Jiewen <jiewen.yao at intel.com>; Laszlo
> Ersek <lersek at redhat.com>
> Subject: [PATCH] CryptoPkg/BaseCryptLib: fix NULL dereference (CVE-2019-
> 14584)
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1914
> 
> 
> 
> AuthenticodeVerify() calls OpenSSLs d2i_PKCS7() API to parse asn encoded
> 
> signed authenticode pkcs#7 data. when this successfully returns, a type
> 
> check is done by calling PKCS7_type_is_signed() and then
> 
> Pkcs7->d.sign->contents->type is used. It is possible to construct an asn1
> 
> blob that successfully decodes and have d2i_PKCS7() return a valid pointer
> 
> and have PKCS7_type_is_signed() also return success  but have Pkcs7->d.sign
> 
> be a NULL pointer.
> 
> 
> 
> Looking at how PKCS7_verify() [inside of OpenSSL] implements checking for
> 
> pkcs7 structs it does the following:
> 
> - call PKCS7_type_is_signed()
> 
> - call PKCS7_get_detached()
> 
> Looking into how PKCS7_get_detatched() is implemented, it checks to see if
> 
> p7->d.sign is NULL or if p7->d.sign->contents->d.ptr is NULL.
> 
> 
> 
> As such, the fix is to do the same as OpenSSL after calling d2i_PKCS7().
> 
> - Add call to PKS7_get_detached() to existing error handling
> 
> 
> 
> Cc: Xiaoyu Lu <xiaoyux.lu at intel.com>
> 
> Cc: Guomin Jiang <guomin.jiang at intel.com>
> 
> Cc: Jiewen Yao <jiewen.yao at intel.com>
> 
> Cc: Laszlo Ersek <lersek at redhat.com>
> Signed-off-by: Jian J Wang <jian.j.wang at intel.com>
> 
> Reviewed-by: Laszlo Ersek <lersek at redhat.com>
> ---
>  CryptoPkg/Library/BaseCryptLib/Pk/CryptAuthenticode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/CryptoPkg/Library/BaseCryptLib/Pk/CryptAuthenticode.c
> b/CryptoPkg/Library/BaseCryptLib/Pk/CryptAuthenticode.c
> index 2772b1e2be..ae0ee61fb6 100644
> --- a/CryptoPkg/Library/BaseCryptLib/Pk/CryptAuthenticode.c
> +++ b/CryptoPkg/Library/BaseCryptLib/Pk/CryptAuthenticode.c
> @@ -9,7 +9,7 @@
>    AuthenticodeVerify() will get PE/COFF Authenticode and will do basic check
> for
> 
>    data structure.
> 
> 
> 
> -Copyright (c) 2011 - 2015, Intel Corporation. All rights reserved.<BR>
> 
> +Copyright (c) 2011 - 2019, Intel Corporation. All rights reserved.<BR>
> 
>  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
> 
> 
>  **/
> 
> @@ -100,7 +100,7 @@ AuthenticodeVerify (
>    //
> 
>    // Check if it's PKCS#7 Signed Data (for Authenticode Scenario)
> 
>    //
> 
> -  if (!PKCS7_type_is_signed (Pkcs7)) {
> 
> +  if (!PKCS7_type_is_signed (Pkcs7) || PKCS7_get_detached (Pkcs7)) {
> 
>      goto _Exit;
> 
>    }
> 
> 
> 
> --
> 2.19.0.windows.1



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