+++ 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@xxxxxxxxxxxxxxx> # v4.15+
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Cc: Jessica Yu <jeyu@xxxxxxxxxx>
Thanks for turning this into a real patch. Looks good to me, if Linus
wants to take it directly:
Acked-by: Jessica Yu <jeyu@xxxxxxxxxx>
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