+++ Thomas Richter [18/04/18 09:14 +0200]:

Reading file /proc/modules shows the correct address: [root@s35lp76 ~]# cat /proc/modules | egrep '^qeth_l2' qeth_l2 94208 1 - Live 0x000003ff80401000

and reading file /sys/module/qeth_l2/sections/.text [root@s35lp76 ~]# cat /sys/module/qeth_l2/sections/.text 0x0000000018ea8363 displays a random address.

This breaks the perf tool which uses this address on s390 to calculate start of .text section in memory.

Fix this by printing the correct (unhashed) address.

Thanks to Jessica Yu for helping on this.

Fixes: ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when not restricting") Cc: stable@vger.kernel.org # v4.15+ Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Thomas Richter tmricht@linux.ibm.com Cc: Jessica Yu jeyu@kernel.org

Thanks for turning this into a real patch. Looks good to me, if Linus wants to take it directly:

Acked-by: Jessica Yu jeyu@kernel.org

Otherwise I can take this up my tree.

As Linus mentioned, we should technically be checking the opening task's credentials/capabilities, but converting everything to pass the actual struct seq_file/file to the sysfs show handlers would be fairly painful :/ At least those /sys/module/*/sections/ files are all set to 0400. I think this fix is sufficient for now.

---

kernel/module.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c index a6e43a5806a1..40b42000bd80 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1472,7 +1472,8 @@ static ssize_t module_sect_show(struct module_attribute *mattr, { struct module_sect_attr *sattr = container_of(mattr, struct module_sect_attr, mattr);

• return sprintf(buf, "0x%pK\n", (void *)sattr->address);

• return sprintf(buf, "0x%px\n", kptr_restrict < 2 ?

•        (void *)sattr->address : NULL);
  

}

static void free_sect_attrs(struct module_sect_attrs *sect_attrs)

2.14.3

On Wed, Apr 18, 2018 at 12:14 AM, Thomas Richter tmricht@linux.ibm.com wrote:

Reading file /proc/modules shows the correct address: [root@s35lp76 ~]# cat /proc/modules | egrep '^qeth_l2' qeth_l2 94208 1 - Live 0x000003ff80401000

and reading file /sys/module/qeth_l2/sections/.text [root@s35lp76 ~]# cat /sys/module/qeth_l2/sections/.text 0x0000000018ea8363 displays a random address.

This breaks the perf tool which uses this address on s390 to calculate start of .text section in memory.

Fix this by printing the correct (unhashed) address.

Thanks to Jessica Yu for helping on this.

Fixes: ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when not restricting") Cc: stable@vger.kernel.org # v4.15+ Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Thomas Richter tmricht@linux.ibm.com Cc: Jessica Yu jeyu@kernel.org

---

kernel/module.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c index a6e43a5806a1..40b42000bd80 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1472,7 +1472,8 @@ static ssize_t module_sect_show(struct module_attribute *mattr, { struct module_sect_attr *sattr = container_of(mattr, struct module_sect_attr, mattr);

•   return sprintf(buf, "0x%pK\n", (void *)sattr->address);
  

•   return sprintf(buf, "0x%px\n", kptr_restrict < 2 ?
  

•                  (void *)sattr->address : NULL);
  

Errr... this looks reversed to me.

I would expect: "kptr_restrict < 2 ? NULL : (void *)sattr->address"

-Kees