Re: [PATCH v2] lib: Use PFN_PHYS() in devmem_is_allowed()

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On 2021/7/30 14:49, Liang Wang wrote:
The physical address may exceed 32 bits on ARM(when ARM_LPAE enabled),
use PFN_PHYS() in devmem_is_allowed(), or the physical address may
overflow and be truncated.

This bug was initially introduced from v2.6.37, and the function was moved
to lib when v5.10.

Fixes: 087aaffcdf9c ("ARM: implement CONFIG_STRICT_DEVMEM by disabling access to RAM via /dev/mem")
Fixes: 527701eda5f1 ("lib: Add a generic version of devmem_is_allowed()")
Cc: stable@xxxxxxxxxxxxxxx # v2.6.37
Signed-off-by: Liang Wang <wangliang101@xxxxxxxxxx>
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
v2: update subject and changelog
  lib/devmem_is_allowed.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c
index c0d67c541849..60be9e24bd57 100644
--- a/lib/devmem_is_allowed.c
+++ b/lib/devmem_is_allowed.c
@@ -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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