From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: regression: crash from 'ls /sys/modules/wl1251_spi/notes' Date: Tue, 5 Jan 2010 17:15:50 -0800 Message-ID: <20100105171550.8aef9b15.akpm@linux-foundation.org> References: <87k4w4wux9.fsf@purkki.valot.fi> <1262188157.2749.21.camel@mulgrave.site> <4B3D145C.2080106@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B3D145C.2080106@gmx.de> Sender: linux-parisc-owner@vger.kernel.org To: Helge Deller Cc: James Bottomley , ben@decadent.org.uk, tbm@cyrius.com, Kalle Valo , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, linux-omap@vger.kernel.org, rusty@rustcorp.com.au, roland@redhat.com, dave@hiauly1.hia.nrc.ca, Parisc List List-Id: linux-omap@vger.kernel.org On Thu, 31 Dec 2009 22:15:08 +0100 Helge Deller wrote: > On 12/30/2009 04:49 PM, James Bottomley wrote: > > A better, and more comprehensive patch would be to try not to count the > > empty text sections when we're building the notes section (and actually > > anywhere else in the file). This patch actually relies on the fact that > > if sh_size is zero for the text section it should be for the > > corresponding notes section. If that doesn't work, we'd actually have > > to do the matching in the construction piece. > > > > Can you try it to see if it works for you? If it doesn't, I'll try > > matching notes to text. It works fine on parisc, but as we don't have a > > notes section, that's not saying much ... > > > > Thanks, > > > > James > > > Ben Hutchings already sent a similar patch. > See: http://patchwork.kernel.org/patch/68925/ > > IMHO James patch below seems better since it > checks if a section will be allocated at a few more > places... > Ben's patch (which is below) is currently in linux-next, via a Rusty tree. It is marked for -stable backporting. If James's patch is preferable then there's an opportunity to do the swap if we move promptly. commit 9e9b48a89ed43c73d7355ff999b8e87b0628e1cd Author: Ben Hutchings AuthorDate: Sat Dec 19 14:43:01 2009 +0000 Commit: Stephen Rothwell CommitDate: Tue Jan 5 08:44:50 2010 +1100 modules: Skip empty sections when exporting section notes Commit 35dead4 "modules: don't export section names of empty sections via sysfs" changed the set of sections that have attributes, but did not change the iteration over these attributes in add_notes_attrs(). This can lead to add_notes_attrs() creating attributes with the wrong names or with null name pointers. Introduce a sect_empty() function and use it in both add_sect_attrs() and add_notes_attrs(). Reported-by: Martin Michlmayr Signed-off-by: Ben Hutchings Tested-by: Martin Michlmayr Cc: stable@kernel.org Signed-off-by: Rusty Russell diff --git a/kernel/module.c b/kernel/module.c index e96b8ed..f82386b 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1010,6 +1010,12 @@ static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs, * J. Corbet */ #if defined(CONFIG_KALLSYMS) && defined(CONFIG_SYSFS) + +static inline bool sect_empty(const Elf_Shdr *sect) +{ + return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0; +} + struct module_sect_attr { struct module_attribute mattr; @@ -1051,8 +1057,7 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect, /* Count loaded sections and allocate structures */ for (i = 0; i < nsect; i++) - if (sechdrs[i].sh_flags & SHF_ALLOC - && sechdrs[i].sh_size) + if (!sect_empty(&sechdrs[i])) nloaded++; size[0] = ALIGN(sizeof(*sect_attrs) + nloaded * sizeof(sect_attrs->attrs[0]), @@ -1070,9 +1075,7 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect, sattr = §_attrs->attrs[0]; gattr = §_attrs->grp.attrs[0]; for (i = 0; i < nsect; i++) { - if (! (sechdrs[i].sh_flags & SHF_ALLOC)) - continue; - if (!sechdrs[i].sh_size) + if (sect_empty(&sechdrs[i])) continue; sattr->address = sechdrs[i].sh_addr; sattr->name = kstrdup(secstrings + sechdrs[i].sh_name, @@ -1156,7 +1159,7 @@ static void add_notes_attrs(struct module *mod, unsigned int nsect, /* Count notes sections and allocate structures. */ notes = 0; for (i = 0; i < nsect; i++) - if ((sechdrs[i].sh_flags & SHF_ALLOC) && + if (!sect_empty(&sechdrs[i]) && (sechdrs[i].sh_type == SHT_NOTE)) ++notes; @@ -1172,7 +1175,7 @@ static void add_notes_attrs(struct module *mod, unsigned int nsect, notes_attrs->notes = notes; nattr = ¬es_attrs->attrs[0]; for (loaded = i = 0; i < nsect; ++i) { - if (!(sechdrs[i].sh_flags & SHF_ALLOC)) + if (sect_empty(&sechdrs[i])) continue; if (sechdrs[i].sh_type == SHT_NOTE) { nattr->attr.name = mod->sect_attrs->attrs[loaded].name;