-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2014-014 ================================= Topic: Multiple vulnerabilities in the mount system call Version: NetBSD-current: source prior to Sun, Apr 20th 2014 NetBSD 6.1.5: not affected NetBSD 6.1 - 6.1.4: affected NetBSD 6.0.6: not affected NetBSD 6.0 - 6.0.5: affected NetBSD 5.1 - 5.1.4: affected NetBSD 5.2 - 5.2.2: affected Severity: Local DoS Fixed: NetBSD-current: Sun, Apr 20th 2014 NetBSD-6-0 branch: Mon, 21 Apr 2014 NetBSD-6-1 branch: Mon, 21 Apr 2014 NetBSD-6 branch: Mon, 21 Apr 2014 NetBSD-5-2 branch: Tue, 29 Apr 2014 NetBSD-5-1 branch: Tue, 29 Apr 2014 NetBSD-5 branch: Sat, 26 Apr 2014 Teeny versions released later than the fix date will contain the fix. Please note that NetBSD releases prior to 5.1 are no longer supported. It is recommended that all users upgrade to a supported release. Abstract ======== Due to: - missing input validation checks in the mount syscall - a wrong assumption on the file systems side - a memory corruption bug the kernel could: - allocate an unbounded or zero-sized memory buffer - dereference a NULL pointer - behave unexpectedly Technical Details ================= The mount syscall takes as fourth and fifth arguments an input buffer and its size. A kernel buffer of the same size is allocated via kmem, and is then handed over to the appropriate file system. This buffer is then freed when no longer needed. The checks on the size of the kernel-allocated buffer were not strict enough, and a local user could easily make the kernel perform a zero- sized or unbounded memory allocation, resulting in a crash. Also, in particular cases, the buffer pointer given to the underlying file systems is allowed to be NULL - some file systems don't need it. The others didn't explicitly check for NULL, and were wrongly making the assumption that it was always a valid, readable buffer, causing the kernel to panic with a page fault. Finally, a bug could corrupt memory when freeing the kernel-allocated buffer. The buffer is freed via kmem_free, whose second argument indicates the size of the allocated buffer. This size was held by a local variable which was modified by the underlying file systems, thus creating a memory inconsistency when freeing which could lead to a crash or unexpected behavior. Solutions and Workarounds ========================= For all NetBSD versions, you need to obtain fixed kernel sources, rebuild and install the new kernel, and reboot the system. The fixed source may be obtained from the NetBSD CVS repository. The following instructions briefly summarise how to upgrade your kernel. In these instructions, replace: ARCH with your architecture (from uname -m), KERNCONF with the name of your kernel configuration file and VERSION with the file version below File versions containing the fixes: files relative to src/sys/fs/: HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- -------- ---------- ---------- -------- ---------- ---------- adosfs/advfsops.c 1.70 1.63.6.1 1.63.12.1 1.63.10.1 1.53.6.1 1.53.20.1 1.53.16.1 cd9660/cd9660_vfsops.c 1.84 1.74.6.1 1.74.12.1 1.74.10.1 1.63.6.2 1.63.6.1.6.1 1.63.6.1.2.1 efs/efs_vfsops.c 1.25 1.22.8.1 1.22.14.1 1.22.12.1 1.16.4.2 1.16.4.1.10.1 1.16.4.1.6.1 filecorefs/filecore_vfsops.c 1.76 1.68.6.1 1.68.12.1 1.68.10.1 1.55.6.1 1.55.20.1 1.55.16.1 hfs/hfs_vfsops.c 1.31 1.27.8.2 1.27.8.1.6.1 1.27.8.1.4.1 1.19.4.1 1.19.16.1 1.19.12.1 msdosfs/msdosfs_vfsops.c 1.107 1.93.6.2 1.93.6.1.6.1 1.93.6.1.4.1 1.68.6.3 1.68.6.2.10.1 1.68.6.2.6.1 nilfs/nilfs_vfsops.c 1.16 1.8.6.1 1.8.12.1 1.8.10.1 n/a n/a n/a ntfs/ntfs_vfsops.c 1.94 1.87.6.1 1.87.20.1 1.87.12.1 1.72.6.2 1.72.6.1.6.1 1.72.6.1.2.1 ptyfs/ptyfs_vfsops.c 1.50 1.42.18.2 1.42.18.1.4.1 1.42.18.1.2.1 1.37.4.1 1.37.18.1 1.37.14.1 puffs/puffs_vfsops.c 1.110 1.100.8.3 1.100.8.2.6.1 1.100.8.2.4.1 1.81.8.4 1.81.8.3.2.1 1.81.8.1.2.1 smbfs/smbfs_vfsops.c 1.100 1.95.8.1 1.95.22.1 1.95.14.1 1.85.4.2 1.85.4.1.6.1 1.85.4.1.2.1 sysvbfs/sysvbfs_vfsops.c 1.43 1.38.6.2 1.38.6.1.6.1 1.38.6.1.4.1 1.26.4.1 1.26.18.1 1.26.14.1 tmpfs/tmpfs_vfsops.c 1.59 1.52.8.1 1.52.22.1 1.52.14.1 1.44.4.1 1.44.22.1 1.44.18.1 udf/udf_vfsops.c 1.67 1.62.6.1 1.62.12.1 1.62.10.1 1.52.2.4 1.52.2.3.6.1 1.52.2.3.2.1 union/union_vfsops.c 1.72 1.67.2.1 1.67.8.1 1.67.6.1 1.57.6.3 1.57.6.2.2.1 1.57.6.1.6.1 unionfs/unionfs_vfsops.c 1.13 1.9.10.1 1.9.18.1 1.9.16.1 1.5.6.1 1.5.16.1 1.5.12.1 v7fs/v7fs_vfsops.c 1.10 1.5.6.2 1.5.6.1.6.1 1.5.6.1.4.1 n/a n/a n/a files relative to src/sys/miscfs/: HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- -------- ---------- ---------- -------- ---------- ---------- nullfs/null_vfsops.c 1.88 1.83.14.1 1.83.20.1 1.83.18.1 1.77.6.1 1.77.16.1 1.77.12.1 overlay/overlay_vfsops.c 1.61 1.56.14.1 1.56.20.1 1.56.18.1 1.53.6.1 1.53.16.1 1.53.12.1 procfs/procfs_vfsops.c 1.91 1.86.8.1 1.86.14.1 1.86.12.1 1.81.6.1 1.81.20.1 1.81.16.1 umapfs/umap_vfsops.c 1.92 1.86.14.1 1.86.20.1 1.86.18.1 1.80.6.1 1.80.16.1 1.80.12.1 files relative to src/sys/ufs/: HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- -------- ---------- ---------- -------- ---------- ---------- chfs/chfs_vfsops.c 1.11 1.2.4.1 1.2.10.1 1.2.8.1 n/a n/a n/a ext2fs/ext2fs_vfsops.c 1.180 1.162.6.1 1.162.12.1 1.162.10.1 1.137.6.7 1.137.6.6.2.1 1.137.6.5.2.1 ffs/ffs_vfsops.c 1.297 1.275.2.3 1.275.2.2.4.1 1.275.2.2.2.1 1.239.2.5 1.239.2.4.6.1 1.239.2.4.2.1 lfs/lfs_vfsops.c 1.321 1.293.2.2 1.293.2.1.6.1 1.293.2.1.4.1 1.267.6.2 1.267.6.1.10.1 1.267.6.1.6.1 mfs/mfs_vfsops.c 1.107 1.103.8.1 1.103.22.1 1.103.14.1 1.98.6.1 1.98.16.1 1.98.12.1 remaining files: HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- -------- ---------- ---------- -------- ---------- ---------- src/external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c 1.12 1.7.2.1 1.7.10.1 1.7.8.1 n/a n/a n/a src/sys/coda/coda_vfsops.c 1.81 1.70.8.1 1.70.14.1 1.70.12.1 1.66.8.1 1.66.22.1 1.66.18.1 src/sys/kern/vfs_syscalls.c 1.482 1.449.2.3 1.449.2.2.6.1 1.449.2.2.4.1 1.376.4.8 1.376.4.7.2.1 1.376.4.5.2.2 src/sys/nfs/nfs_vfsops.c 1.227 1.220.8.1 1.220.16.1 1.220.14.1 1.203.4.1 1.203.14.1 1.203.10.1 To update from CVS, re-build, and re-install the kernel: # cd src # cvs update -d -P -r VERSION \ external/cddl/osnet/dist/uts/common/fs/zfs/zfs_vfsops.c # cvs update -d -P -r VERSION sys/coda/coda_vfsops.c # cvs update -d -P -r VERSION sys/fs/adosfs/advfsops.c # cvs update -d -P -r VERSION sys/fs/cd9660/cd9660_vfsops.c # cvs update -d -P -r VERSION sys/fs/efs/efs_vfsops.c # cvs update -d -P -r VERSION sys/fs/filecorefs/filecore_vfsops.c # cvs update -d -P -r VERSION sys/fs/hfs/hfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/msdosfs/msdosfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/nilfs/nilfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/ntfs/ntfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/ptyfs/ptyfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/puffs/puffs_vfsops.c # cvs update -d -P -r VERSION sys/fs/smbfs/smbfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/sysvbfs/sysvbfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/tmpfs/tmpfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/udf/udf_vfsops.c # cvs update -d -P -r VERSION sys/fs/union/union_vfsops.c # cvs update -d -P -r VERSION sys/fs/unionfs/unionfs_vfsops.c # cvs update -d -P -r VERSION sys/fs/v7fs/v7fs_vfsops.c # cvs update -d -P -r VERSION sys/kern/vfs_syscalls.c # cvs update -d -P -r VERSION sys/miscfs/nullfs/null_vfsops.c # cvs update -d -P -r VERSION sys/miscfs/overlay/overlay_vfsops.c # cvs update -d -P -r VERSION sys/miscfs/procfs/procfs_vfsops.c # cvs update -d -P -r VERSION sys/miscfs/umapfs/umap_vfsops.c # cvs update -d -P -r VERSION sys/nfs/nfs_vfsops.c # cvs update -d -P -r VERSION sys/ufs/chfs/chfs_vfsops.c # cvs update -d -P -r VERSION sys/ufs/ext2fs/ext2fs_vfsops.c # cvs update -d -P -r VERSION sys/ufs/ffs/ffs_vfsops.c # cvs update -d -P -r VERSION sys/ufs/lfs/lfs_vfsops.c # cvs update -d -P -r VERSION sys/ufs/mfs/mfs_vfsops.c # ./build.sh kernel=KERNCONF # mv /netbsd /netbsd.old # cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd # shutdown -r now For more information on how to do this, see: http://www.NetBSD.org/guide/en/chap-kernel.html Thanks To ========= Thanks to Maxime Villard, Christos Zoulas and matthew green; Maxime Villard for finding the issues and all three for developing fixes. Note ==== It is to be noted that despite the long, unusual time the NetBSD Foundation took to release this Security Advisory, the fixes listed above were applied and propagated to the stable branches as soon as the vulnerabilities were discovered. Revision History ================ 2014-11-03 Initial release More Information ================ Advisories may be updated as new information becomes available. The most recent version of this advisory (PGP signed) can be found at http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2014-014.txt.asc Information about NetBSD and NetBSD security can be found at http://www.NetBSD.org/ and http://www.NetBSD.org/Security/ . Copyright 2014, The NetBSD Foundation, Inc. All Rights Reserved. Redistribution permitted only in full, unmodified form. $NetBSD: NetBSD-SA2014-014.txt,v 1.2 2014/11/03 09:09:54 spz Exp $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (NetBSD) iQIcBAEBAgAGBQJUV/DWAAoJEAZJc6xMSnBuNLgP/AnDp79AhVChEzy0RadpTO2Z xOPhtl9Dd8XCQ/UgIYEs1F0Z0yR31g7vrC+d5T6Y81UV+AR+2DtecUmWyc4rTSH9 sCQZFKNWocYh61AFiKMb8INnYp5a0KHK4HcD/mFeQKf3fhpJG9JrgDLzHoa7oqde N/gUt6sPdRGpTjBpdBcHX2H9o1w9s/3YY0VGimTzNCyKK1cnKNn1m4+sWnQp2nvC 507uUeyxIfX4QWtFeErRnijynLsVnBsC5MasOz7/EgEfIAQ+2LHOcEPkUf7Z7iMg Lupz733aGahRYKud64LrNtunZ7BLDfxKkZ4Csf5NhKPudw7paNdmgOy++/ENqBNS SmtCDf7i7ooH4mCHmKhD15oFXK+RQaJRp9yLzJ2KWDsukVu3Unt8xUXEc28L5LTd Ng3DaZDU9h0QdCgYsbkqQQk+82iraJWqkap0eZEVVv6jgzsutvzC2mcdufprjhIw eIlpcOEYiwVPUnKEfwpz9lwVCYgBORDTBAwTXxjZFNn/MsBh5cqYN7fio1KFwRPO xSnA2EQOOfw3rVosQt6kAk7Mal/X9ylxshU32l6EjokHwSXyXYswcXRu3E9VV2bX acFNypOhjIic3oeIxqIljzZzvmi3TebWkv/AOChaDkbShpklvmRd5FsSAJOKbNd/ Z5cyxU2JgFao3/aVxP/S =dGEn -----END PGP SIGNATURE-----