[PATCH 5.4 071/154] ARM: Remove address checking for MMUless devices

Greg Kroah-Hartman
2025-04-08T12:06:36Z

From: Yanjun Yang <yangyj.ee@gmail.com>

commit 3ccea4784fddd96fbd6c4497eb28b45dab638c2a upstream.

Commit 169f9102f9198b ("ARM: 9350/1: fault: Implement
copy_from_kernel_nofault_allowed()") added the function to check address
before use. However, for devices without MMU, addr > TASK_SIZE will
always fail. This patch move this function after the #ifdef CONFIG_MMU
statement.

Signed-off-by: Yanjun Yang <yangyj.ee@gmail.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218953
Fixes: 169f9102f9198b ("ARM: 9350/1: fault: Implement copy_from_kernel_nofault_allowed()")
Link: https://lore.kernel.org/r/20240611100947.32241-1-yangyj.ee@gmail.com
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/mm/fault.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -25,6 +25,8 @@

#include "fault.h"

+#ifdef CONFIG_MMU
+
bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
{
unsigned long addr = (unsigned long)unsafe_src;
@@ -32,8 +34,6 @@ bool copy_from_kernel_nofault_allowed(co
return addr >= TASK_SIZE && ULONG_MAX - addr >= size;
}

-#ifdef CONFIG_MMU
-
/*
* This is useful to dump out the page tables associated with
* 'addr' in mm 'mm'.