From owner-freebsd-net@freebsd.org Sun Apr 24 03:01:36 2016 Return-Path: Delivered-To: freebsd-net@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 4AE47B112E4 for ; Sun, 24 Apr 2016 03:01:36 +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 1E75D1DF5 for ; Sun, 24 Apr 2016 03:01:36 +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 u3O31ZWh013447 for ; Sun, 24 Apr 2016 03:01:35 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-net@FreeBSD.org Subject: [Bug 208985] DoS / heap overflow in bpf_stats_sysctl Date: Sun, 24 Apr 2016 03:01:36 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-CURRENT X-Bugzilla-Keywords: patch X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: csjp@sqrt.ca X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-net@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 Apr 2016 03:01:36 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D208985 csjp@sqrt.ca changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |csjp@sqrt.ca --- Comment #2 from csjp@sqrt.ca --- This thought had crossed my mind when I implemented this. This is one of the reasons I don't like the sysctl(2) interface for this sort of thing. It's a= lso subject to race conditions when the number of BPF descriptors change after = the size calculation but before we retrieve the data. The main reason I didn't bound check the size was for two reasons: the amou= nt of data to allocate is a function of the number of BPF descriptors that are allocated. There isn't a limit on this (outside of the file descriptor limitations). The second reason you point out, is this operation requires privilege. The reason I make the statement in the comment is because although by default o= nly root can open this device, it is possible (though not very likely) that the permissions were changed on the underlying BPF device node, resulting in a = BPF descriptor being created by somebody who wasn't root. I don't believe the patch as written is correct either, because there is no connection to this value and the number of descriptors which could be in us= e at the time the stats are retrieved. Having said that, I don't think its a bad idea to bounds check this value either. --=20 You are receiving this mail because: You are the assignee for the bug.=