[Karmic] SRU: Upstream detected regression in 2.6.31.7

[Leann Ogasawara]

On Mon, 2009-12-21 at 18:06 +0100, Stefan Bader wrote:
> SRU Justification:
> 
> Impact: Upstream stable patch apparently introduced a regression with
> 2.6.31.7 (missed to change one of the affected places).
> 
> Fix: This fix was sent to upstream (cc: stable). It is not (yet)
> integrated in upstream, but as soon as it does I'd like to pull
> that in together with the 2.6.31.7 we are reviewing.
> 
> Testcase: see below

Acked-by: Leann Ogasawara <leann.ogasawara at canonical.com>

> ---
> 
> 
> Subject: [PATCH] modules: Skip empty sections when exporting section notes
> From: Ben Hutchings <ben at decadent.org.uk>
> Date: Sat, 19 Dec 2009 14:43:01 +0000
> To: Rusty Russell <rusty at rustcorp.com.au>
> CC: Helge Deller <deller at gmx.de>, Martin Michlmayr <tbm at cyrius.com>, LKML <linux-kernel at vger.kernel.org>
> 
> 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 <tbm at cyrius.com>
> Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
> Tested-by: Martin Michlmayr <tbm at cyrius.com>
> Cc: stable at kernel.org
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  kernel/module.c |   17 ++++++++++-------
>  1 files changed, 10 insertions(+), 7 deletions(-)
> 
> 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 <corbet at lwn.net>
>   */
>  #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 = &sect_attrs->attrs[0];
>  	gattr = &sect_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 = &notes_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;
> --
>