From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48475) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ai6gM-0000I6-Se for qemu-devel@nongnu.org; Mon, 21 Mar 2016 16:44:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ai6gJ-0000hx-GS for qemu-devel@nongnu.org; Mon, 21 Mar 2016 16:44:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59474) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ai6gJ-0000hU-AF for qemu-devel@nongnu.org; Mon, 21 Mar 2016 16:44:07 -0400 From: Markus Armbruster Date: Mon, 21 Mar 2016 21:43:24 +0100 Message-Id: <1458593043-31731-2-git-send-email-armbru@redhat.com> In-Reply-To: <1458593043-31731-1-git-send-email-armbru@redhat.com> References: <1458593043-31731-1-git-send-email-armbru@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL v2 01/40] target-ppc: Document TOCTTOU in hugepage support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Michael Roth The code to find the minimum page size is is vulnerable to TOCTTOU. Added in commit 2d103aa "target-ppc: fix hugepage support when using memory-backend-file" (v2.4.0). Since I can't fix it myself right now, add a FIXME comment. Cc: Paolo Bonzini Cc: Michael Roth Signed-off-by: Markus Armbruster Message-Id: <1458066895-20632-2-git-send-email-armbru@redhat.com> Reviewed-by: Marc-Andr=C3=A9 Lureau --- target-ppc/kvm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index 776336b..2fc9931 100644 --- a/target-ppc/kvm.c +++ b/target-ppc/kvm.c @@ -333,6 +333,12 @@ static long gethugepagesize(const char *mem_path) return fs.f_bsize; } =20 +/* + * FIXME TOCTTOU: this iterates over memory backends' mem-path, which + * may or may not name the same files / on the same filesystem now as + * when we actually open and map them. Iterate over the file + * descriptors instead, and use qemu_fd_getpagesize(). + */ static int find_max_supported_pagesize(Object *obj, void *opaque) { char *mem_path; --=20 2.4.3