NetBSD Problem Report #60645

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Date: Wed, 26 Aug 2026 02:08:05 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: nfssvc(2): arithmetic overflow in input array sizing
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X-From4GNATS: "campbell+netbsd@mumble.net via gnats" <gnats-admin@NetBSD.org>

>Number:         60645
>Category:       kern
>Synopsis:       nfssvc(2): arithmetic overflow in input array sizing
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          pending-pullups
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Aug 26 02:10:00 +0000 2026
>Closed-Date:    
>Last-Modified:  Sun Oct 25 10:55:01 +0000 2026
>Originator:     Taylor R Campbell
>Release:        current, 11, 10, 9, ...
>Organization:
The NetBSD Filexportation, In)3^=$,*%928:5%-%76)0
>Environment:
>Description:

	Unchecked multiplication for an array malloc can lead to
	overflow and various downstream consequences:

    343 	} else if (flag & (NFSSVC_SETEXPORTSLIST | NFSSVC_REPLACEEXPORTSLIST)) {
    344 		struct export_args *args;
    345 		struct mountd_exports_list mel;
    346 
    347 		error = ops->setexports_in(&mel, argp);
    348 		if (error != 0)
    349 			return error;
    350 
    351 		args = (struct export_args *)malloc(mel.mel_nexports *
    352 		    sizeof(struct export_args), M_TEMP, M_WAITOK);
    353 		error = ops->exp_in(args, mel.mel_exports, mel.mel_nexports);

	https://nxr.netbsd.org/xref/src/sys/nfs/nfs_syscalls.c?r=1.165#343

>How-To-Repeat:

	code inspection

	export a file system too many different ways

>Fix:

	set a maximum number of exports per mount point

>Release-Note:

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: src/sys/nfs
Date: Wed, 26 Aug 2026 02:59:47 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Aug 26 02:59:47 UTC 2026

 Modified Files:
 	src/sys/nfs: nfs_syscalls.c

 Log Message:
 nfs_syscalls.c: Sort includes.

 No functional change intended.

 Preparation for:

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.165 -r1.166 src/sys/nfs/nfs_syscalls.c

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: src/sys/nfs
Date: Wed, 26 Aug 2026 03:01:25 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Aug 26 03:01:25 UTC 2026

 Modified Files:
 	src/sys/nfs: nfs_export.c nfs_syscalls.c nfs_var.h

 Log Message:
 nfs: New sysctl node vfs.nfsd.maxexportspermount.

 Limits the number of different ways a single mount point can be
 exported.  Default is limited to 256; can be expanded by sysctl up to
 anything that won't overflow kva.

 XXX Should prevent increasing it at securelevel>0.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.63 -r1.64 src/sys/nfs/nfs_export.c
 cvs rdiff -u -r1.166 -r1.167 src/sys/nfs/nfs_syscalls.c
 cvs rdiff -u -r1.97 -r1.98 src/sys/nfs/nfs_var.h

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: src/sys/nfs
Date: Wed, 26 Aug 2026 03:28:56 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Aug 26 03:28:56 UTC 2026

 Modified Files:
 	src/sys/nfs: nfs_syscalls.c

 Log Message:
 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS on amd64 rump.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.167 -r1.168 src/sys/nfs/nfs_syscalls.c

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: src/sys/nfs
Date: Wed, 26 Aug 2026 12:48:02 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Aug 26 12:48:01 UTC 2026

 Modified Files:
 	src/sys/nfs: nfs_syscalls.c

 Log Message:
 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS in rump.

 Let's get the builds unbroken before making this perfect.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.168 -r1.169 src/sys/nfs/nfs_syscalls.c

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

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: src/sys/nfs
Date: Wed, 26 Aug 2026 13:28:37 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Aug 26 13:28:37 UTC 2026

 Modified Files:
 	src/sys/nfs: nfs_export.c nfs_syscalls.c nfs_var.h

 Log Message:
 nfs: On reflection, just clamp the export_args buffer to 64 KiB.

 Keep it simple, just make sure userland doesn't trigger contiguous
 kva allocation of more than 64 KiB.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.64 -r1.65 src/sys/nfs/nfs_export.c
 cvs rdiff -u -r1.169 -r1.170 src/sys/nfs/nfs_syscalls.c
 cvs rdiff -u -r1.98 -r1.99 src/sys/nfs/nfs_var.h

 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, 17 Sep 2026 00:08:03 +0000
State-Changed-Why:
fixed in HEAD, needs pullup-11, pullup-10


State-Changed-From-To: needs-pullups->pending-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Wed, 21 Oct 2026 03:10:08 +0000
State-Changed-Why:
pullup-11 #552
pullup-10 #1396


From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/60645 CVS commit: [netbsd-11] src/sys/nfs
Date: Sun, 25 Oct 2026 10:48:17 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sun Oct 25 10:48:17 UTC 2026

 Modified Files:
 	src/sys/nfs [netbsd-11]: nfs_syscalls.c

 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #552):

 	sys/nfs/nfs_syscalls.c: revision 1.166
 	sys/nfs/nfs_syscalls.c: revision 1.167
 	sys/nfs/nfs_var.h: revision 1.98
 	sys/nfs/nfs_syscalls.c: revision 1.168
 	sys/nfs/nfs_var.h: revision 1.99
 	sys/nfs/nfs_syscalls.c: revision 1.169
 	sys/nfs/nfs_export.c: revision 1.64
 	sys/nfs/nfs_export.c: revision 1.65
 	sys/nfs/nfs_syscalls.c: revision 1.170

 nfs_syscalls.c: Sort includes.

 No functional change intended.

 Preparation for:
 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: New sysctl node vfs.nfsd.maxexportspermount.

 Limits the number of different ways a single mount point can be
 exported.  Default is limited to 256; can be expanded by sysctl up to
 anything that won't overflow kva.

 XXX Should prevent increasing it at securelevel>0.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS on amd64 rump.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS in rump.

 Let's get the builds unbroken before making this perfect.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: On reflection, just clamp the export_args buffer to 64 KiB.
 Keep it simple, just make sure userland doesn't trigger contiguous
 kva allocation of more than 64 KiB.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.164.2.1 -r1.164.2.2 src/sys/nfs/nfs_syscalls.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/60645 CVS commit: [netbsd-10] src/sys/nfs
Date: Sun, 25 Oct 2026 10:50:07 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Sun Oct 25 10:50:07 UTC 2026

 Modified Files:
 	src/sys/nfs [netbsd-10]: nfs_syscalls.c

 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #1396):

 	sys/nfs/nfs_syscalls.c: revision 1.166
 	sys/nfs/nfs_syscalls.c: revision 1.167
 	sys/nfs/nfs_var.h: revision 1.98
 	sys/nfs/nfs_syscalls.c: revision 1.168
 	sys/nfs/nfs_var.h: revision 1.99
 	sys/nfs/nfs_syscalls.c: revision 1.169
 	sys/nfs/nfs_export.c: revision 1.64
 	sys/nfs/nfs_export.c: revision 1.65
 	sys/nfs/nfs_syscalls.c: revision 1.170

 nfs_syscalls.c: Sort includes.

 No functional change intended.

 Preparation for:
 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: New sysctl node vfs.nfsd.maxexportspermount.

 Limits the number of different ways a single mount point can be
 exported.  Default is limited to 256; can be expanded by sysctl up to
 anything that won't overflow kva.

 XXX Should prevent increasing it at securelevel>0.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS on amd64 rump.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: Work around missing VM_MIN/MAX_KERNEL_ADDRESS in rump.

 Let's get the builds unbroken before making this perfect.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing

 nfs: On reflection, just clamp the export_args buffer to 64 KiB.
 Keep it simple, just make sure userland doesn't trigger contiguous
 kva allocation of more than 64 KiB.

 PR kern/60645: nfssvc(2): arithmetic overflow in input array sizing


 To generate a diff of this commit:
 cvs rdiff -u -r1.163.10.1 -r1.163.10.2 src/sys/nfs/nfs_syscalls.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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