From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932311Ab2GKTKk (ORCPT ); Wed, 11 Jul 2012 15:10:40 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:56518 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756648Ab2GKTKe (ORCPT ); Wed, 11 Jul 2012 15:10:34 -0400 MIME-Version: 1.0 In-Reply-To: <20120711183239.GA7122@redhat.com> References: <20120711183239.GA7122@redhat.com> From: Linus Torvalds Date: Wed, 11 Jul 2012 12:10:12 -0700 X-Google-Sender-Auth: Kcyhi5KHzjjhHcE3vEBwtonZD0U Message-ID: Subject: Re: 3.5-rc6 dentry related GPF To: Dave Jones , Linux Kernel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 11, 2012 at 11:32 AM, Dave Jones wrote: > > What's puzzling me though is how we got from do_dentry_open to try_module_get ? It's the f->f_op = fops_get(inode->i_fop); that does it. I have no idea what the actual bug is, though, but the code decodes to 0: 89 75 f0 mov %esi,-0x10(%rbp) 3: 4c 89 7d f8 mov %r15,-0x8(%rbp) 7: 66 66 66 66 90 data32 data32 data32 xchg %ax,%ax c: b8 01 00 00 00 mov $0x1,%eax 11: 48 85 ff test %rdi,%rdi 14: 48 89 fb mov %rdi,%rbx 17: 74 42 je 0x5b 19: 65 48 8b 04 25 b0 c8 mov %gs:0xc8b0,%rax 20: 00 00 22: 83 80 44 e0 ff ff 01 addl $0x1,-0x1fbc(%rax) 29:* 83 3f 02 cmpl $0x2,(%rdi) <-- trapping instruction 2c: 0f 84 54 01 00 00 je 0x186 32: 48 8b 87 50 02 00 00 mov 0x250(%rdi),%rax 39: 65 48 ff 00 incq %gs:(%rax) where that "cmpl $2" is the "module_is_live(module)" test, as far as I can tell. And %rdi should be the module pointer, but it is obviously garbage: rdi = 54415541e5894855 which looks like some odd corrupted ASCII to me ("UH\211\345AUAT") but that makes no sense either. Linus