NetBSD Problem Report #60485

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Date: Thu, 23 Jul 2026 17:13:48 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: pf(4): uaf in fragment reassembly
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X-From4GNATS: "campbell+netbsd@mumble.net via gnats" <gnats-admin@NetBSD.org>

>Number:         60485
>Category:       kern
>Synopsis:       pf(4): uaf in fragment reassembly
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          pending-pullups
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 23 17:15:00 +0000 2026
>Closed-Date:    
>Last-Modified:  Sun Aug 02 13:30:02 +0000 2026
>Originator:     Taylor R Campbell
>Release:        current, 11, 10, 9, ...
>Organization:
The UafPF Foundation, Inc.
>Environment:
>Description:

	pf(4) fragment reassembly may lead to use-after-free of a pf
	mbuf tag.

   5759 	if ((pf_mtag = pf_get_mtag(m)) == NULL) {
...
   5762 		return (PF_DROP);
   5763 	}
...
   5771 	/* We do IP header normalization and packet reassembly here */
   5772 	if (pf_normalize_ip(m0, dir, kif, &reason, &pd) != PF_PASS) {
   5773 		action = PF_DROP;
   5774 		goto done;
   5775 	}
   5776 	m = *m0;	/* pf_normalize messes with m0 */
...
   5969 		pf_mtag->flags |= PF_TAG_TRANSLATE_LOCALHOST;

https://nxr.netbsd.org/xref/src/sys/dist/pf/net/pf.c?r=1.87#5758

	pf_normalize_ip can change the identity of *m0, so the pf_mtag
	previously obtained from m may have been freed.

	Forwarded to us by Chris Jarrett-Davies <chrisjd@openai.com>.

>How-To-Repeat:

	1. configure pf to reassemble fragments
	2. send fragments

	(turn on asan or whatever to actually detect it)

>Fix:

	Re-acquire pf_mtag from the replacement mbuf.

>Release-Note:

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60485 CVS commit: src/sys/dist/pf/net
Date: Thu, 23 Jul 2026 17:17:10 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Jul 23 17:17:10 UTC 2026

 Modified Files:
 	src/sys/dist/pf/net: pf.c

 Log Message:
 pf(4): Avoid UAF of pf mbuf tag in fragment reassembly.

 PR kern/60485: pf(4): uaf in fragment reassembly


 To generate a diff of this commit:
 cvs rdiff -u -r1.87 -r1.88 src/sys/dist/pf/net/pf.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->needs-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Thu, 23 Jul 2026 21:04:07 +0000
State-Changed-Why:
fixed in HEAD, needs pullup-11, pullup-10, pullup-9
(and maybe we should just delete pf, I'm sure this is not the only
remotely triggerable issue in our ancient version of it)


State-Changed-From-To: needs-pullups->pending-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Sat, 25 Jul 2026 19:48:48 +0000
State-Changed-Why:
pullup-11 #398 https://releng.netbsd.org/cgi-bin/req-11.cgi?show=398
pullup-10 #1318 https://releng.netbsd.org/cgi-bin/req-10.cgi?show=1318
pullup-9 #2040 https://releng.netbsd.org/cgi-bin/req-9.cgi?show=2040


From: "Stephen Borrill" <sborrill@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60485 CVS commit: [netbsd-9] src/sys/dist/pf/net
Date: Tue, 28 Jul 2026 11:27:28 +0000

 Module Name:	src
 Committed By:	sborrill
 Date:		Tue Jul 28 11:27:28 UTC 2026

 Modified Files:
 	src/sys/dist/pf/net [netbsd-9]: pf.c

 Log Message:
 Pull up the following revisions(s) (requested by riastradh in ticket #2040):
 	sys/dist/pf/net/pf.c:	revision 1.88

 pf: Fix use-after-free in fragment reassembly.
 PR kern/60485: pf(4): uaf in fragment reassembly


 To generate a diff of this commit:
 cvs rdiff -u -r1.83 -r1.83.4.1 src/sys/dist/pf/net/pf.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Stephen Borrill" <sborrill@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60485 CVS commit: [netbsd-10] src/sys/dist/pf/net
Date: Tue, 28 Jul 2026 13:39:25 +0000

 Module Name:	src
 Committed By:	sborrill
 Date:		Tue Jul 28 13:39:25 UTC 2026

 Modified Files:
 	src/sys/dist/pf/net [netbsd-10]: pf.c

 Log Message:
 Pull up the following revisions(s) (requested by riastradh in ticket #1318):
 	sys/dist/pf/net/pf.c:	revision 1.88

 pf: Fix use-after-free in fragment reassembly.
 PR kern/60485: pf(4): uaf in fragment reassembly


 To generate a diff of this commit:
 cvs rdiff -u -r1.87 -r1.87.2.1 src/sys/dist/pf/net/pf.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60485 CVS commit: [netbsd-11] src/sys/dist/pf/net
Date: Sun, 2 Aug 2026 13:26:25 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sun Aug  2 13:26:25 UTC 2026

 Modified Files:
 	src/sys/dist/pf/net [netbsd-11]: pf.c

 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #398):

 	sys/dist/pf/net/pf.c: revision 1.88

 pf(4): Avoid UAF of pf mbuf tag in fragment reassembly.

 PR kern/60485: pf(4): uaf in fragment reassembly


 To generate a diff of this commit:
 cvs rdiff -u -r1.87 -r1.87.10.1 src/sys/dist/pf/net/pf.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

>Unformatted:

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