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

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[ Upstream commit 5a06fcb15b ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Arnd Bergmann 2022-02-16 13:48:06 +01:00 • committed by Justin Hammond
parent cc1bf28bb5
commit 886dc06022
1 changed files with 8 additions and 3 deletions
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11
lib/test_lockup.c
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@ -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;