Bug 1188235 – CVE-2015-1472 glibc: heap buffer overflow in glibc swscanf

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Bug 1188235 - (CVE-2015-1472) CVE-2015-1472 glibc: heap buffer overflow in glibc swscanf

Summary:	CVE-2015-1472 glibc: heap buffer overflow in glibc swscanf

Status:	CLOSED ERRATA

Aliases:	CVE-2015-1472

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	low Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=low,public=20140221,reported=2...
Keywords:	Reopened, Security

Depends On:	1188237 1209106 1209107 1242303
Blocks:	1188240 1210268 1262918
	Show dependency tree / graph

Reported:	2015-02-02 06:45 EST by Vasyl Kaigorodov
Modified:	2016-06-13 07:56 EDT (History)
CC List:	13 users (show)

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:	A heap-based buffer overflow flaw was found in glibc's swscanf() function. An attacker able to make an application call the swscanf() function could use this flaw to crash that application or, potentially, execute arbitrary code with the permissions of the user running the application.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2015-11-20 00:49:53 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Sourceware	16618	None	None	None	Never
Red Hat Product Errata	RHSA-2015:2199	normal	SHIPPED_LIVE	Moderate: glibc security, bug fix, and enhancement update	2015-11-19 03:04:22 EST
Red Hat Product Errata	RHSA-2015:2589	normal	SHIPPED_LIVE	Important: glibc security update	2015-12-09 08:57:25 EST

Groups: None (edit)

Description Vasyl Kaigorodov 2015-02-02 06:45:11 EST

Heap buffer overflow was reported [1] in glibc stdio-common/vfscanf.c.

stdio-common/vfscanf.c has an ADDW macro that tries to determine whether to use malloc or alloca for allocations.  But in the malloc case, it only allocates newsize bytes instead of the required newsize * sizeof (CHAR_T).  Thus the allocated buffer gets overrun in the wide-string case, as shown in the following testcase:

  int
  main (void)
  {
    wchar_t *s = malloc ((SIZE + 1) * sizeof (*s));
    if (s == NULL)
      abort ();
    for (size_t i = 0; i < SIZE; i++)
      s[i] = L'0';
    s[SIZE] = L'\0';
    int i;
    if (swscanf (s, L"%d", &i) != 1)
      abort ();
    if (i != 0)
      abort ();
    free (s);
    return 0;
  }

CVE request: http://www.openwall.com/lists/oss-security/2015/02/01/8

[1]: https://sourceware.org/bugzilla/show_bug.cgi?id=16618

Comment 1 Vasyl Kaigorodov 2015-02-02 06:45:40 EST

Created glibc tracking bugs for this issue:

Affects: fedora-all [bug 1188237]

Comment 2 Carlos O'Donell 2015-02-06 00:53:36 EST

Now fixed in upstream.

commit 5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06
Author: Paul Pluzhnikov <ppluzhnikov@google.com>
Date:   Fri Feb 6 00:30:42 2015 -0500

    CVE-2015-1472: wscanf allocates too little memory
    
    BZ #16618
    
    Under certain conditions wscanf can allocate too little memory for the
    to-be-scanned arguments and overflow the allocated buffer.  The
    implementation now correctly computes the required buffer size when
    using malloc.
    
    A regression test was added to tst-sscanf.

Comment 3 Tomas Hoger 2015-02-06 03:30:43 EST

https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=5bd80bfe9ca0d955bfbbc002781bc7b01b6bcb06

Comment 6 Fedora Update System 2015-03-04 05:26:52 EST

glibc-2.20-8.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 9 Vasyl Kaigorodov 2015-05-21 11:59:53 EDT

Statement:

This issue did not affect the versions of glibc as shipped with Red Hat Enterprise Linux 5 and 6 as they did use different memory allocation algorithm in swscanf() function.

Comment 11 errata-xmlrpc 2015-11-18 23:16:04 EST

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:2199 https://rhn.redhat.com/errata/RHSA-2015-2199.html

Comment 12 errata-xmlrpc 2015-12-09 03:58:14 EST

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.1 EUS - Server and Compute Node Only
  Red Hat Enterprise Linux 7.1 EUS  - Server and Compute Node Only

Via RHSA-2015:2589 https://rhn.redhat.com/errata/RHSA-2015-2589.html

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