public inbox for devel@edk2.groups.io
 help / color / mirror / Atom feed
From: Jian J Wang <jian.j.wang@intel.com>
To: edk2-devel@lists.01.org
Cc: Michael D Kinney <michael.d.kinney@intel.com>,
	Liming Gao <liming.gao@intel.com>,
	Jiewen Yao <jiewen.yao@intel.com>,
	Star Zeng <star.zeng@intel.com>
Subject: [PATCH v2 2/2] MdeModulePkg/DxePrintLibPrint2Protocol: Fix potential string over read
Date: Thu, 28 Dec 2017 10:38:28 +0800	[thread overview]
Message-ID: <20171228023828.18752-3-jian.j.wang@intel.com> (raw)
In-Reply-To: <20171228023828.18752-1-jian.j.wang@intel.com>

> v2:
>    Add in v2

Due to a potential hole in the stop condition of loop, the two continuous
access to ArgumentString (index, index+1) inside the loop might cause the
string ending character ('\0') and the byte after it to be read.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 MdeModulePkg/Library/DxePrintLibPrint2Protocol/PrintLib.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Library/DxePrintLibPrint2Protocol/PrintLib.c b/MdeModulePkg/Library/DxePrintLibPrint2Protocol/PrintLib.c
index 56534e56c3..570d06d82e 100644
--- a/MdeModulePkg/Library/DxePrintLibPrint2Protocol/PrintLib.c
+++ b/MdeModulePkg/Library/DxePrintLibPrint2Protocol/PrintLib.c
@@ -2050,7 +2050,10 @@ InternalPrintLibSPrintMarker (
       // Compute the number of characters in ArgumentString and store it in Count
       // ArgumentString is either null-terminated, or it contains Precision characters
       //
-      for (Count = 0; Count < Precision || ((Flags & PRECISION) == 0); Count++) {
+      for (Count = 0;
+            ArgumentString[Count * BytesPerArgumentCharacter] != '\0' &&
+            Count < Precision || ((Flags & PRECISION) == 0);
+            Count++) {
         ArgumentCharacter = ((ArgumentString[Count * BytesPerArgumentCharacter] & 0xff) | ((ArgumentString[Count * BytesPerArgumentCharacter + 1]) << 8)) & ArgumentMask;
         if (ArgumentCharacter == 0) {
           break;
@@ -2107,7 +2110,7 @@ InternalPrintLibSPrintMarker (
     //
     // Copy the string into the output buffer performing the required type conversions
     //
-    while (Index < Count) {
+    while (Index < Count && (*ArgumentString) != '\0') {
       ArgumentCharacter = ((*ArgumentString & 0xff) | (((UINT8)*(ArgumentString + 1)) << 8)) & ArgumentMask;
 
       LengthToReturn += (1 * BytesPerOutputCharacter);
-- 
2.15.1.windows.2



  parent reply	other threads:[~2017-12-28  2:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-28  2:38 [PATCH v2 0/2] Fix error in PrintLib Jian J Wang
2017-12-28  2:38 ` [PATCH v2 1/2] MdePkg/BasePrintLib: Fix error in Precision position calculation Jian J Wang
     [not found]   ` <CAKv+Gu_W-0etAXve+1Vn-hDL9A-9Oror-L6nCtt9_UqRxkhhCw@mail.gmail.com>
2018-01-02  8:23     ` Wang, Jian J
2017-12-28  2:38 ` Jian J Wang [this message]
2017-12-28  2:43 ` [PATCH v2 0/2] Fix error in PrintLib Gao, Liming
2017-12-28  3:10 ` Zeng, Star
2017-12-29  1:07 ` Kinney, Michael D
2017-12-29  1:41   ` Wang, Jian J

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-list from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20171228023828.18752-3-jian.j.wang@intel.com \
    --to=devel@edk2.groups.io \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox