-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2014-010 ================================= Topic: Multiple vulnerabilities in the compatibility layers Version: NetBSD-current: source prior to Tue, Apr 15th 2014 NetBSD 6.1 - 6.1.4: 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: Tue, Apr 15th 2014 NetBSD-6-0 branch: Mon, Apr 21th 2014 NetBSD-6-1 branch: Mon, Apr 21th 2014 NetBSD-6 branch: Mon, Apr 21th 2014 NetBSD-5-2 branch: Wed, May 14th 2014 NetBSD-5-1 branch: Wed, May 14th 2014 NetBSD-5 branch: Wed, May 14th 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 ======== Four compatibility layers are affected by several vulnerabilities: 1) FreeBSD compatibility: NULL pointer dereference 2) NetBSD 32-bit compatibility: Zero-sized memory allocation 3) Digital UNIX (formerly OSF/1) compatibility: Zero-sized memory allocation 4) Linux and Linux 32-bit compatibility: User-controllable kernel memory array index. Each of them allows a local user to crash the system. Technical Details ================= For more clarity the four layers affected will be referred to as COMPAT_xx, where xx is the emulated system. 1) Due to a programming mistake in COMPAT_FREEBSD, a simple call to the sched_getparam system call would cause the kernel to dereference a NULL pointer, and thus to crash. 2) Due to a missing input validation check in COMPAT_NETBSD32's kevent system call, a user could cause the kernel to perform a zero-sized memory allocation, resulting in a crash. 3) Due to a missing input validation check in COMPAT_OSF1's getdirentries system call, a user could cause the kernel to perform a zero-sized memory allocation, resulting in a crash. 4) Due to missing input validation checks in the COMPAT_LINUX and COMPAT_LINUX32 ELF binary loader, a specially-crafted binary could control a kernel memory array index - address from which data is read. Attempting to read from an unmapped memory page will cause the kernel to crash. Solutions and Workarounds ========================= Disable the compability modules +------------------------------ You can achieve this with the modunload(8) tool. Please read the appropriate manual page. For example, you can disable the Linux modules by moving the kernel object files out of the way. These are located in: /stand/${MACHINE_ARCH}/${KERNEL_VERSION}/modules/compat_${NAME}/compat_${NAME}.kmod And running the following command to unload them: # modunload compat_${NAME} The modules have dependencies, so you need to unload them in the proper order. You can also disable these modules by rebuilding your kernel without the COMPAT_${NAME} options. Note however that it is to be considered as a temporary workaround, and you are strongly advised to fix your system from source. Fix from source +-------------- 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: FILE HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- ---- -------- ---------- ---------- -------- ---------- ---------- src/sys/compat/freebsd/freebsd_sched.c 1.20 1.19.40.1 1.19.56.1 1.19.46.1 1.19.10.1 1.19.48.1 1.19.24.1 src/sys/compat/netbsd32/netbsd32_compat_50.c 1.24 1.20.6.1 1.20.14.1 1.20.12.1 XXXXXXXX XXXXXXXXXX XXXXXXXXXX src/sys/compat/netbsd32/netbsd32_event.c 1.11 1.9.10.2 1.9.24.1 1.9.16.1 XXXXXXXX XXXXXXXXXX XXXXXXXXXX src/sys/compat/osf1/osf1_file.c 1.42 1.41.8.1 1.41.22.1 1.41.14.1 XXXXXXXX XXXXXXXXXX XXXXXXXXXX src/sys/compat/linux/common/linux_exec_elf32.c 1.91 1.86.2.1 1.86.16.1 1.86.8.1 1.81.10.1 1.81.20.1 1.81.16.1 To update from CVS, re-build, and re-install the kernel: # cd src # cvs update -d -P -r VERSION sys/compat/freebsd/freebsd_sched.c # cvs update -d -P -r VERSION sys/compat/netbsd32/netbsd32_compat_50.c # cvs update -d -P -r VERSION sys/compat/netbsd32/netbsd32_event.c # cvs update -d -P -r VERSION sys/compat/osf1/osf1_file.c # cvs update -d -P -r VERSION sys/compat/linux/common/linux_exec_elf32.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, Martin Husemann, Chuck Silvers, Enami Tsugutomo and Matt Thomas for finding, fixing and helping in fixing these issues. Revision History ================ 2014-08-27 Initial release 2014-09-08 Updated pullup version numbers from OSF1 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-SA2014-010.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-SA2014-010.txt,v 1.5 2014/09/06 13:02:00 maxv Exp $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUDhAiAAoJEAZJc6xMSnBuSiYP/32ab/iRXHEfu9jcgSia+H4F 0rISYVDEk5Vzr5ffeTvHCi8JOOls3g8e/O+jxxtQP/RcrvpLncGHcNReccBThCqK oJas4N+f6gxH/TkXGk6tQnr6b8ppuW1on5HhSEH/olMZ5E13kzxqRngXgGBCIVEP +kNGJ5PwxF+dqo64ZZ/dutW+Vghp+FHJ9QmMekfl2U4FB1tZT/Q1Js/dM23n0/O1 h2FFjXNSv9SU6uFiBf45tS1fM996MtOiHzVUKu86XQatNSnYNWAyeUqaIWG+1MxY i0IjCw1LKBkBeLJ1KAcOG3xWAfn1gLtiJI2uQZMx4hfoxZjxajp2bA+iZrl+8lcM 8TfAIfcmHdNt/qUOa2dfIGiHFlYth81eHDnLDOBpvuXQ96MhBcAUhRQaP5Dp8Aj/ 54/ZMkydfJVguQgtPMAOYScgPKuou2lvYStP5ToODYQppuAnF0Byz2KN+EORuw0E 2CjFC1SPNPEs5gKYZTac7OBLUl6ZChv5ZtrPCcWY6gWEoW2VCQHMiqXcSYOPrvTh x97wPu//Dnpfbx6g3aD9ZsoQEOTqXgdkGATwY+gnuX558zfQ+gsu+jUbzRm+Jej3 tJpTiQCDVpxHMWt4jFH4W1nmhc4w5N0JJ0MW2OLN2xvjgU717Fec9cIKkXoIYSEj bnqzoegVXB42QC4cAeHT =4ykv -----END PGP SIGNATURE-----