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Old 12-21-2009, 04:06 PM
Stefan Bader
 
Default SRU: Upstream detected regression in 2.6.31.7

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

---


Subject: [PATCH] modules: Skip empty sections when exporting section notes
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 19 Dec 2009 14:43:01 +0000
To: Rusty Russell <rusty@rustcorp.com.au>
CC: Helge Deller <deller@gmx.de>, Martin Michlmayr <tbm@cyrius.com>, LKML <linux-kernel@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@cyrius.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Tested-by: Martin Michlmayr <tbm@cyrius.com>
Cc: stable@kernel.org
Signed-off-by: Stefan Bader <stefan.bader@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@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;
--

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Old 12-21-2009, 04:26 PM
Leann Ogasawara
 
Default SRU: Upstream detected regression in 2.6.31.7

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@canonical.com>

> ---
>
>
> Subject: [PATCH] modules: Skip empty sections when exporting section notes
> From: Ben Hutchings <ben@decadent.org.uk>
> Date: Sat, 19 Dec 2009 14:43:01 +0000
> To: Rusty Russell <rusty@rustcorp.com.au>
> CC: Helge Deller <deller@gmx.de>, Martin Michlmayr <tbm@cyrius.com>, LKML <linux-kernel@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@cyrius.com>
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> Tested-by: Martin Michlmayr <tbm@cyrius.com>
> Cc: stable@kernel.org
> Signed-off-by: Stefan Bader <stefan.bader@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@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;
> --
>



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