printk: use %pK for /proc/kallsyms and /proc/modules
In an effort to reduce kernel address leaks that might be used to help
target kernel privilege escalation exploits, this patch uses %pK when
displaying addresses in /proc/kallsyms, /proc/modules, and
/sys/module/*/sections/*.
Note that this changes %x to %p, so some legitimately 0 values in
/proc/kallsyms would have changed from 00000000 to "(null)". To avoid
this, "(null)" is not used when using the "K" format. Anything that was
already successfully parsing "(null)" in addition to full hex digits
should have no problem with this change. (Thanks to Joe Perches for the
suggestion.) Due to the %x to %p, "void *" casts are needed since these
addresses are already "unsigned long" everywhere internally, due to their
starting life as ELF section offsets.
Signed-off-by: Kees Cook <kees.cook@canonical.com>
Cc: Eugene Teo <eugene@redhat.com>
Cc: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 6f6d091..75dcca3 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -477,13 +477,11 @@
*/
type = iter->exported ? toupper(iter->type) :
tolower(iter->type);
- seq_printf(m, "%0*lx %c %s\t[%s]\n",
- (int)(2 * sizeof(void *)),
- iter->value, type, iter->name, iter->module_name);
+ seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
+ type, iter->name, iter->module_name);
} else
- seq_printf(m, "%0*lx %c %s\n",
- (int)(2 * sizeof(void *)),
- iter->value, iter->type, iter->name);
+ seq_printf(m, "%pK %c %s\n", (void *)iter->value,
+ iter->type, iter->name);
return 0;
}
diff --git a/kernel/module.c b/kernel/module.c
index efa290e..1f9f7bc 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1168,7 +1168,7 @@
{
struct module_sect_attr *sattr =
container_of(mattr, struct module_sect_attr, mattr);
- return sprintf(buf, "0x%lx\n", sattr->address);
+ return sprintf(buf, "0x%pK\n", (void *)sattr->address);
}
static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
@@ -3224,7 +3224,7 @@
mod->state == MODULE_STATE_COMING ? "Loading":
"Live");
/* Used by oprofile and other similar tools. */
- seq_printf(m, " 0x%p", mod->module_core);
+ seq_printf(m, " 0x%pK", mod->module_core);
/* Taints info */
if (mod->taints)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 070d134..ac444ff 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -991,7 +991,7 @@
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
struct printf_spec spec)
{
- if (!ptr) {
+ if (!ptr && *fmt != 'K') {
/*
* Print (null) with the same width as a pointer so it makes
* tabular output look nice.
