From 854f32648b8a5e424d682953b1a9f3b7c3322701 Mon Sep 17 00:00:00 2001 From: Liang Wang Date: Fri, 13 Aug 2021 16:54:45 -0700 Subject: [PATCH] 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: 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()") Signed-off-by: Liang Wang Reviewed-by: Luis Chamberlain Cc: Palmer Dabbelt Cc: Greg Kroah-Hartman Cc: Russell King Cc: Liang Wang Cc: Xiaoming Ni Cc: Kefeng Wang Cc: [2.6.37+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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;