Commit 5a06fcb1 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

lib/test_lockup: fix kernel pointer check for separate address spaces 



test_kernel_ptr() uses access_ok() to figure out if a given address
points to user space instead of kernel space. However on architectures
that set CONFIG_ALTERNATE_USER_ADDRESS_SPACE, a pointer can be valid
for both, and the check always fails because access_ok() returns true.

Make the check for user space pointers conditional on the type of
address space layout.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 12700c17

lib/test_lockup.c

+8 −3
Original line number Diff line number Diff line
@@ -417,9 +417,14 @@ static bool test_kernel_ptr(unsigned long addr, int size) 
		return false;



	/* should be at least readable kernel address */

	if (access_ok((void __user *)ptr, 1) ||

	    access_ok((void __user *)ptr + size - 1, 1) ||

	    get_kernel_nofault(buf, ptr) ||

	if (!IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) &&

	    (access_ok((void __user *)ptr, 1) ||

	     access_ok((void __user *)ptr + size - 1, 1))) {

		pr_err("user space ptr invalid in kernel: %#lx\n", addr);

		return true;

	}



	if (get_kernel_nofault(buf, ptr) ||

	    get_kernel_nofault(buf, ptr + size - 1)) {

		pr_err("invalid kernel ptr: %#lx\n", addr);

		return true;