From owner-freebsd-bugs@freebsd.org Wed Oct 28 18:15:04 2015 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9A399A1F4BF for ; Wed, 28 Oct 2015 18:15:04 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 6D84B1B66 for ; Wed, 28 Oct 2015 18:15:04 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id t9SIF4CA024516 for ; Wed, 28 Oct 2015 18:15:04 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 204097] witness_initialize() does not perform bound checking of witness_count Date: Wed, 28 Oct 2015 18:15:04 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: ertl.chris@gmail.com X-Bugzilla-Status: New X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Oct 2015 18:15:04 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204097 Bug ID: 204097 Summary: witness_initialize() does not perform bound checking of witness_count Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: ertl.chris@gmail.com The witness_count sysctl node is of type CTLFLAG_RDTUN, which means it's a read-only variable, but can be set during boot by creating a "debug.witness.count" entry in /boot/loader.conf. The witness_initialize() function of sys/kern/subr_witness.c does not perform bound checks on witness_count which could lead to integer overflows, and memory corruption. The following line from witness_initialize() can cause an overflow, if witness_count is 2147483647 for example, since a signed comparison is used: for (i = 0; i < witness_count + 1; i++) { This means that the w_rmatrix[i] buffers are never allocated, which would lead to kernel reads and writes from an uninitialized pointer. A potential fix would be to add the following bound check at the beginning of the function: if (witness_count < 0 || witness_count >= 2147483647) { printf("Invalid witness_count value of %d, setting to 2147483646\n", witness_count); witness_count = 2147483646; } -- You are receiving this mail because: You are the assignee for the bug.