From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43584) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afto6-0006cA-G1 for qemu-devel@nongnu.org; Tue, 15 Mar 2016 14:35:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1afto3-0001lD-8u for qemu-devel@nongnu.org; Tue, 15 Mar 2016 14:35:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48643) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afto3-0001l4-3a for qemu-devel@nongnu.org; Tue, 15 Mar 2016 14:34:59 -0400 From: Markus Armbruster Date: Tue, 15 Mar 2016 19:34:16 +0100 Message-Id: <1458066895-20632-2-git-send-email-armbru@redhat.com> In-Reply-To: <1458066895-20632-1-git-send-email-armbru@redhat.com> References: <1458066895-20632-1-git-send-email-armbru@redhat.com> Subject: [Qemu-devel] [PATCH v3 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: claudio.fontana@huawei.com, Michael Roth , david.marchand@6wind.com, mlureau@redhat.com, pbonzini@redhat.com, cam@cs.ualberta.ca 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 --- target-ppc/kvm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index d67c169..5be57a7 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; } +/* + * 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; -- 2.4.3