From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] lkdtm: Add a tests for NULL pointer dereference
Date: Fri, 14 Dec 2018 15:26:20 +0000 (UTC) [thread overview]
Message-ID: <8593f7faf89812a9987d44d9ae615d64dca4d77f.1544800744.git.christophe.leroy@c-s.fr> (raw)
Introduce lkdtm tests for NULL pointer dereference: check
access or exec at NULL address.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
drivers/misc/lkdtm/core.c | 2 ++
drivers/misc/lkdtm/lkdtm.h | 2 ++
drivers/misc/lkdtm/perms.c | 18 ++++++++++++++++++
3 files changed, 22 insertions(+)
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index bc76756b7eda..36910e1d5c09 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -157,7 +157,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(EXEC_VMALLOC),
CRASHTYPE(EXEC_RODATA),
CRASHTYPE(EXEC_USERSPACE),
+ CRASHTYPE(EXEC_NULL),
CRASHTYPE(ACCESS_USERSPACE),
+ CRASHTYPE(ACCESS_NULL),
CRASHTYPE(WRITE_RO),
CRASHTYPE(WRITE_RO_AFTER_INIT),
CRASHTYPE(WRITE_KERN),
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index 3c6fd327e166..b69ee004a3f7 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -45,7 +45,9 @@ void lkdtm_EXEC_KMALLOC(void);
void lkdtm_EXEC_VMALLOC(void);
void lkdtm_EXEC_RODATA(void);
void lkdtm_EXEC_USERSPACE(void);
+void lkdtm_EXEC_NULL(void);
void lkdtm_ACCESS_USERSPACE(void);
+void lkdtm_ACCESS_NULL(void);
/* lkdtm_refcount.c */
void lkdtm_REFCOUNT_INC_OVERFLOW(void);
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index fa54add6375a..62f76d506f04 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -164,6 +164,11 @@ void lkdtm_EXEC_USERSPACE(void)
vm_munmap(user_addr, PAGE_SIZE);
}
+void lkdtm_EXEC_NULL(void)
+{
+ execute_location(NULL, CODE_AS_IS);
+}
+
void lkdtm_ACCESS_USERSPACE(void)
{
unsigned long user_addr, tmp = 0;
@@ -195,6 +200,19 @@ void lkdtm_ACCESS_USERSPACE(void)
vm_munmap(user_addr, PAGE_SIZE);
}
+void lkdtm_ACCESS_NULL(void)
+{
+ unsigned long tmp;
+ unsigned long *ptr = (unsigned long *)NULL;
+
+ pr_info("attempting bad read at %px\n", ptr);
+ tmp = *ptr;
+ tmp += 0xc0dec0de;
+
+ pr_info("attempting bad write at %px\n", ptr);
+ *ptr = tmp;
+}
+
void __init lkdtm_perms_init(void)
{
/* Make sure we can write to __ro_after_init values during __init */
--
2.13.3
next reply other threads:[~2018-12-14 15:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 15:26 Christophe Leroy [this message]
2019-01-09 1:14 ` [PATCH] lkdtm: Add a tests for NULL pointer dereference Kees Cook
2019-01-09 6:31 ` Christophe Leroy
2019-01-09 15:16 ` Kees Cook
2019-01-09 20:05 ` Kees Cook
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