NetBSD Problem Report #53474

From www@NetBSD.org  Thu Jul 26 14:11:59 2018
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Date: Thu, 26 Jul 2018 14:11:58 +0000 (UTC)
From: zh_jq@outlook.com
Reply-To: zh_jq@outlook.com
To: gnats-bugs@NetBSD.org
Subject: mmap get anon execuable memory return MAP_FAILED
X-Send-Pr-Version: www-1.0

>Number:         53474
>Category:       kern
>Synopsis:       mmap get anon execuable memory return MAP_FAILED
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 26 14:15:00 +0000 2018
>Closed-Date:    Thu Jul 26 14:23:34 +0000 2018
>Last-Modified:  Fri Jul 27 10:25:00 +0000 2018
>Originator:     Zhang Jingqiang
>Release:        8.0
>Organization:
>Environment:
NetBSD localhost 8.0 NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018  mkrepro@mkrepro.NetBSD.org:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
When use mmap to allocate MAP_ANON executable memory, it always returns MAP_FAILED.
This makes pcre2_jit_compile returns NOMEMORY error, as they use this in "src/sljit/sljitExecAllocator.c".
>How-To-Repeat:
Use the following test program:
--
#include <stdio.h>
#include <sys/mman.h>

int main(int argc, char *argv[])
{
        void *retval = mmap(NULL, 4096, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
        printf("retval: %p\n", retval);
        return 0;
}
--

Compile using the following command:
--
gcc -o test test.c
--

Then run ./test, you will get
  retval: 0xffffffffffffffff

But if we run the program with gdb, it works as expected.
And if remove PROT_EXEC, the program works also.
>Fix:

>Release-Note:

>Audit-Trail:

State-Changed-From-To: open->closed
State-Changed-By: martin@NetBSD.org
State-Changed-When: Thu, 26 Jul 2018 14:23:34 +0000
State-Changed-Why:
Not a bug


From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
Date: Thu, 26 Jul 2018 16:22:53 +0200

 On Thu, Jul 26, 2018 at 02:15:00PM +0000, zh_jq@outlook.com wrote:
 >         void *retval = mmap(NULL, 4096, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);

 You can not create writable + executable mappings when pax mprotect is
 active (which is the default on many architectures). See mremap(2).

 Martin


From: =?utf-8?B?5bygIOaVrOW8ug==?= <zh_jq@outlook.com>
To: "gnats-bugs@netbsd.org" <gnats-bugs@netbsd.org>
Cc: Martin Husemann <martin@duskware.de>
Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
Date: Thu, 26 Jul 2018 15:04:56 +0000

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From: Joerg Sonnenberger <joerg@bec.de>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
Date: Thu, 26 Jul 2018 22:53:23 +0200

 On Thu, Jul 26, 2018 at 02:25:00PM +0000, Martin Husemann wrote:
 > The following reply was made to PR kern/53474; it has been noted by GNATS.
 > 
 > From: Martin Husemann <martin@duskware.de>
 > To: gnats-bugs@NetBSD.org
 > Cc: 
 > Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
 > Date: Thu, 26 Jul 2018 16:22:53 +0200
 > 
 >  On Thu, Jul 26, 2018 at 02:15:00PM +0000, zh_jq@outlook.com wrote:
 >  >         void *retval = mmap(NULL, 4096, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
 >  
 >  You can not create writable + executable mappings when pax mprotect is
 >  active (which is the default on many architectures). See mremap(2).

 Also, this has nothing to do with MAP_ANON.

 Joerg

From: ? ?? <zh_jq@outlook.com>
To: "gnats-bugs@netbsd.org" <gnats-bugs@netbsd.org>
Cc: Martin Husemann <martin@duskware.de>
Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
Date: Thu, 26 Jul 2018 15:19:44 +0000

 Sorry, resend again, as the previous one has been changed by outlook.com
 >  On Thu, Jul 26, 2018 at 02:15:00PM +0000, zh_jq@outlook.com wrote:
 >  >         void *retval =3D mmap(NULL, 4096, PROT_READ | PROT_WRITE |
 >  >         PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
 >  You can not create writable + executable mappings when pax mprotect is
 >  active (which is the default on many architectures). See mremap(2).
 OK, got it.
 I will write a bug report to pcre2.
 As a temprate solution I will disable security.pax.mprotect.enabled.
 Thanks



From: Joerg Sonnenberger <joerg@bec.de>
To: gnats-bugs@NetBSD.org
Cc: kern-bug-people@netbsd.org, gnats-admin@netbsd.org,
	netbsd-bugs@netbsd.org, zh_jq@outlook.com
Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
Date: Fri, 27 Jul 2018 12:21:39 +0200

 On Thu, Jul 26, 2018 at 10:40:01PM +0000, ? ?? wrote:
 > The following reply was made to PR kern/53474; it has been noted by GNATS.
 > 
 > From: ? ?? <zh_jq@outlook.com>
 > To: "gnats-bugs@netbsd.org" <gnats-bugs@netbsd.org>
 > Cc: Martin Husemann <martin@duskware.de>
 > Subject: Re: kern/53474: mmap get anon execuable memory return MAP_FAILED
 > Date: Thu, 26 Jul 2018 15:19:44 +0000
 > 
 >  Sorry, resend again, as the previous one has been changed by outlook.com
 >  >  On Thu, Jul 26, 2018 at 02:15:00PM +0000, zh_jq@outlook.com wrote:
 >  >  >         void *retval =3D mmap(NULL, 4096, PROT_READ | PROT_WRITE |
 >  >  >         PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
 >  >  You can not create writable + executable mappings when pax mprotect is
 >  >  active (which is the default on many architectures). See mremap(2).
 >  OK, got it.
 >  I will write a bug report to pcre2.
 >  As a temprate solution I will disable security.pax.mprotect.enabled.

 pkgsrc/devel/libffi/patches/patch-src_closures.c illustrates a possible
 fix.

 Joerg

>Unformatted:

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