Re: [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces
From: Christoph Hellwig <hch@lst.de>
Date: 2022-02-18 06:36:02
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linux-alpha, linux-arch, linux-m68k, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, linux-um, linuxppc-dev, lkml, sparclinux
On Wed, Feb 16, 2022 at 02:13:28PM +0100, Arnd Bergmann wrote:
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.
What is this code even trying to do? It looks extremly broken.