Bug 1289022

Summary:	VLAs not protected with -fstack-protector
Product:	Red Hat Enterprise Linux 7	Reporter:	Jakub Jelinek <jakub>
Component:	gcc	Assignee:	Jakub Jelinek <jakub>
Status:	CLOSED ERRATA	QA Contact:	Michael Petlan <mpetlan>
Severity:	unspecified	Docs Contact:	Tomas Capek <tcapek>
Priority:	unspecified
Version:	7.3	CC:	mcermak, mpetlan, mpolacek, ohudlick
Target Milestone:	rc
Target Release:	7.3
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	gcc-4.8.5-6.el7	Doc Type:	Bug Fix
Doc Text:	Better stack protection in GCC Prior to this update, GCC stack protection did not work for functions that only contained variable-length arrays and no other (or only very small) arrays. Consequently, a buffer overflow error could occur undetected. This bug has been fixed and the compiler is now able to instrument even such functions.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-11-04 06:27:17 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1297579, 1313485

Description Jakub Jelinek 2015-12-07 09:17:07 UTC

In GCC 4.7+, gcc mistakenly does not stack protect functions that contain just a variable length array and no other (or only very small) arrays.
See http://gcc.gnu.org/PR68680 for details, just use -fstack-protector instead of -fstack-protector-strong.

E.g. -O2 -fstack-protector:

int process(char *);

int
uses_vla(unsigned long sz)
{
  char buf[sz];
  return process(buf);
}

Comment 3 Michael Petlan 2016-07-25 09:48:51 UTC

test fails with gcc-4.8.5-4.el7
test passes for gcc-4.8.5-9.el7

VERIFIED

Comment 5 errata-xmlrpc 2016-11-04 06:27:17 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-2433.html