Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752843Ab3JQHX2 (ORCPT ); Thu, 17 Oct 2013 03:23:28 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:55193 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751144Ab3JQHX1 convert rfc822-to-8bit (ORCPT ); Thu, 17 Oct 2013 03:23:27 -0400 Message-Id: <525FAC8B02000078000FBAE8@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Thu, 17 Oct 2013 08:23:23 +0100 From: "Jan Beulich" To: "Andrew Morton" Cc: , , , Subject: Re: [PATCH] fix proc_reg_get_unmapped_area() References: <525E957802000078000FB6FE@nat28.tlf.novell.com> <20131016134044.d1bd8004f4fb94df405a541d@linux-foundation.org> In-Reply-To: <20131016134044.d1bd8004f4fb94df405a541d@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2839 Lines: 69 >>> On 16.10.13 at 22:40, Andrew Morton wrote: > On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" wrote: > >> Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device >> proc file mmap(2)"), while fixing one problem, introduced two new ones: >> - the function truncates the return value from ->get_unmapped_area() on >> 64-bit architectures, >> - _all_ descendants are now required to set .get_unmapped_area to non- >> NULL, which wasn't necessary before (and shouldn't be). >> >> Both - afaict - are a result from a too simplistic copy'n'paste from >> proc_reg_mmap() done in that change. >> >> This likely also addresses reports like the one at >> > http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729 > 326.html. >> >> ... >> >> --- 3.12-rc5/fs/proc/inode.c >> +++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c >> @@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi >> static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned > long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags) >> { >> struct proc_dir_entry *pde = PDE(file_inode(file)); >> - int rv = -EIO; >> - unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned > long, unsigned long, unsigned long); >> + unsigned long rv = -EIO; >> + >> if (use_pde(pde)) { >> - get_unmapped_area = pde->proc_fops->get_unmapped_area; >> - if (get_unmapped_area) >> - rv = get_unmapped_area(file, orig_addr, len, pgoff, flags); >> + rv = (pde->proc_fops->get_unmapped_area >> + ?: current->mm->get_unmapped_area)(file, orig_addr, len, >> + pgoff, flags); >> unuse_pde(pde); >> } >> return rv; > > I think these two patches will address the problems: > > http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-retur > ned-mapped-address.patch > http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on- > mmu-present-architectures.patch > > I'll be sending those Linuswards today. Please check them. (I think > your version would break the nommu build). Yes indeed - I did search for existing patches, but didn't find them. I see Linus merged them already, so there's no point anymore sending Reviewed-by tags. I think though that in the !MMU case the second of them leaves an issue unfixed nevertheless: If the specific procfs handler has no .get_unmapped_area, the operation would still fail in that case rather than succeed as it did before that wrapper got added.) Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/