-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2014-011 =================================
Topic: User-controlled memory allocation in the modctl system call Version: NetBSD-current: source prior to Thu, Jul 10th 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: Thu, Jul 10th 2014 NetBSD-6-1 branch: Mon, Jul 14th 2014 NetBSD-6-0 branch: Mon, Jul 14th 2014 NetBSD-6 branch: Mon, Jul 14th 2014 NetBSD-5.2 branch: Mon, Jul 14th 2014 NetBSD-5.1 branch: Mon, Jul 14th 2014 NetBSD-5 branch: Mon, Jul 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 ======== Due to missing input validation checks, a local (un)privileged user could cause the kernel to perform a zero-sized or unbounded memory allocation, resulting in a crash. Technical Details ================= The modctl system call takes as second argument a buffer which is represented as a structure when loading a kernel module. This structure indicates special information on how to load a module, including a string pointer and the length of the string pointed to. A kernel buffer of the same size is allocated, but no check was performed to ensure the size is neither too low nor too high, thus allowing a local user to crash the system. 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: FILE HEAD netbsd-6 netbsd-6-1 netbsd-6-0 netbsd-5 netbsd-5-2 netbsd-5-1 ---- ---- -------- ---------- ---------- -------- ---------- ---------- sys/kern/sys_module.c 1.15 1.13.8.1 1.13.14.1 1.13.12.1 1.8.4.2 1.8.4.1.6.1 1.8.4.1.2.1 To update from CVS, re-build, and re-install the kernel: # cd src # cvs update -d -P -r VERSION sys/kern/sys_module.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, who found the issue and provided a fix. Revision History ================ 2014-08-27 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-SA2014-011.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-SA2014-011.txt,v 1.3 2014/08/30 07:00:29 maxv Exp $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUDhArAAoJEAZJc6xMSnBuHygP/juhVWWrWtPQQzGbCE9Jksqn SEvyoNvSNtjUdp+1gSqsZe8x7xYg2DNaGqvVORYVm9fpP7Kn5//7ub1GaI1PNbVP +7Vn4jtNs+jeMrhLo5yAhSilb3DorRTIzvhkyNmU1P9zwAaHuV1PNIjBDkmXN3mL JbxSf6/X5xcSl3gCmE6UE+sQ45bvLVMnKEv0cuNO6CLxf0YKuJCTyp6Wh55bzjPq Vw64j2WLB1mU/EVhF7GHHQ1QhnpoGnZ1UwYxVlqeH1dR+9RPYj1Kjh784kDOVN6K j2yulxDLrz07we1IEqmWW7slLK3qWRARLJgEDd6NEiB677GImuYDRYtEdUFI/wSV NcoDXCAoFeFuvZUqjFCbKmcC0bBrfoBbRLvuLyogAZ51iAbUpJpUwn6BamftcRo/ 2qKwdNDbaqXvXTGeaF98DKR+RsiG69Z1P9l2OmzSV29Jn2WC9Tz5Dbh2Dd5fsHQV t0tCCApbI2UiLu4OFi9DhxhraiO0gBlPaTjtnc1fnyLapjw4lZFo2q6xnHmrtj4l CYTQuVghHly4yeDHPMISpipmgzx9Z/lQadUejbv65j1Id4PLMPSezNKzSZJRy+D2 I7cv0rn0nT2PVDNRbmsVpZCiJjILKI4GXcwpXfKEma/dEeqJjuClwe5P/zZffYOx 4y8sbEeOXHwBqmF76e+d =wcom -----END PGP SIGNATURE-----