[PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces
From: Arnd Bergmann <arnd@kernel.org>
Date: 2022-02-16 13:19:30
Also in:
linux-alpha, linux-api, linux-arch, linux-m68k, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, linux-um, lkml, sparclinux
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
From: Arnd Bergmann <arnd@arndb.de> 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: Arnd Bergmann <arnd@arndb.de> --- lib/test_lockup.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/lib/test_lockup.c b/lib/test_lockup.c
index 6a0f329a794a..c3fd87d6c2dd 100644
--- a/lib/test_lockup.c
+++ b/lib/test_lockup.c@@ -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;
--
2.29.2