[PATCH 06/11] lkdtm: disable set_fs-based tests for !CONFIG_SET_FS

Christoph Hellwig
2020-08-17T07:33:14Z

Once we can't manipulate the address limit, we also can't test what
happens when the manipulation is abused.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/misc/lkdtm/bugs.c | 2 ++
drivers/misc/lkdtm/core.c | 4 ++++
drivers/misc/lkdtm/usercopy.c | 2 ++
3 files changed, 8 insertions(+)

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 4dfbfd51bdf774..66f1800b1cb82d 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -312,6 +312,7 @@ void lkdtm_CORRUPT_LIST_DEL(void)
pr_err("list_del() corruption not detected!\n");
}

+#ifdef CONFIG_SET_FS
/* Test if unbalanced set_fs(KERNEL_DS)/set_fs(USER_DS) check exists. */
void lkdtm_CORRUPT_USER_DS(void)
{
@@ -321,6 +322,7 @@ void lkdtm_CORRUPT_USER_DS(void)
/* Make sure we do not keep running with a KERNEL_DS! */
force_sig(SIGKILL);
}
+#endif

/* Test that VMAP_STACK is actually allocating with a leading guard page */
void lkdtm_STACK_GUARD_PAGE_LEADING(void)
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index a5e344df916632..aae08b33a7ee2a 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -112,7 +112,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(CORRUPT_STACK_STRONG),
CRASHTYPE(CORRUPT_LIST_ADD),
CRASHTYPE(CORRUPT_LIST_DEL),
+#ifdef CONFIG_SET_FS
CRASHTYPE(CORRUPT_USER_DS),
+#endif
CRASHTYPE(STACK_GUARD_PAGE_LEADING),
CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
CRASHTYPE(UNSET_SMEP),
@@ -172,7 +174,9 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
CRASHTYPE(USERCOPY_STACK_BEYOND),
CRASHTYPE(USERCOPY_KERNEL),
+#ifdef CONFIG_SET_FS
CRASHTYPE(USERCOPY_KERNEL_DS),
+#endif
CRASHTYPE(STACKLEAK_ERASING),
CRASHTYPE(CFI_FORWARD_PROTO),
#ifdef CONFIG_X86_32
diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
index b833367a45d053..4b632fe79ab6bb 100644
--- a/drivers/misc/lkdtm/usercopy.c
+++ b/drivers/misc/lkdtm/usercopy.c
@@ -325,6 +325,7 @@ void lkdtm_USERCOPY_KERNEL(void)
vm_munmap(user_addr, PAGE_SIZE);
}

+#ifdef CONFIG_SET_FS
void lkdtm_USERCOPY_KERNEL_DS(void)
{
char __user *user_ptr =
@@ -339,6 +340,7 @@ void lkdtm_USERCOPY_KERNEL_DS(void)
pr_err("copy_to_user() to noncanonical address succeeded!?\n");
set_fs(old_fs);
}
+#endif

void __init lkdtm_usercopy_init(void)
{
--
2.28.0