From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Arnd Bergmann Subject: [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces Date: Wed, 16 Feb 2022 14:13:28 +0100 Message-Id: <20220216131332.1489939-15-arnd@kernel.org> In-Reply-To: <20220216131332.1489939-1-arnd@kernel.org> References: <20220216131332.1489939-1-arnd@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk Cc: linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, ebiederm@xmission.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org List-ID: From: Arnd Bergmann 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 --- 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