path: root/lib
diff options
authorLiang Wang <>2021-08-13 16:54:45 -0700
committerLinus Torvalds <>2021-08-13 14:09:32 -1000
commit854f32648b8a5e424d682953b1a9f3b7c3322701 (patch)
treed7c0a4ce894d98ef3aff49ac6ef6c305bda958a1 /lib
parent7fa0dacbaf1259fd3d1dda6d602fdd084dea9c0e (diff)
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: 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 <>
Diffstat (limited to 'lib')
1 files changed, 1 insertions, 1 deletions
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;