Commit 854f3264 authored by Liang Wang's avatar Liang Wang Committed by Linus Torvalds

lib: use PFN_PHYS() in devmem_is_allowed()

The physical address may exceed 32 bits on 32-bit systems with more than
32 bits of physcial address.  Use PFN_PHYS() in devmem_is_allowed(), or
the physical address may overflow and be truncated.

We found this bug when mapping a high addresses through devmem tool,
when CONFIG_STRICT_DEVMEM is enabled on the ARM with ARM_LPAE and devmem
is used to map a high address that is not in the iomem address range, an
unexpected error indicating no permission is returned.

This bug was initially introduced from v2.6.37, and the function was
moved to lib in v5.11.

Link: https://lkml.kernel.org/r/20210731025057.78825-1-wangliang101@huawei.com
Fixes: 087aaffc ("ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem")
Fixes: 527701ed ("lib: Add a generic version of devmem_is_allowed()")
Signed-off-by: default avatarLiang Wang <wangliang101@huawei.com>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Liang Wang <wangliang101@huawei.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>	[2.6.37+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7fa0dacb
......@@ -19,7 +19,7 @@
*/
int devmem_is_allowed(unsigned long pfn)
{
if (iomem_is_exclusive(pfn << PAGE_SHIFT))
if (iomem_is_exclusive(PFN_PHYS(pfn)))
return 0;
if (!page_is_ram(pfn))
return 1;
......
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