[ Upstream commit c8a43c18a97845e7f94ed7d181c11f41964976a2 ]
When KASLR is enabled (CONFIG_RANDOMIZE_BASE=y), the top 4K of kernel virtual address space may be mapped to physical addresses despite being reserved for ERR_PTR values.
Fix the randomization of the linear region so that we avoid mapping the last page of the virtual address space.
Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: liyueyi liyueyi@live.com [will: rewrote commit message; merged in suggestion from Ard] Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin (Microsoft) sashal@kernel.org --- arch/arm64/mm/init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index caa295cd5d09..9e6c822d458d 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -447,7 +447,7 @@ void __init arm64_memblock_init(void) * memory spans, randomize the linear region as well. */ if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) { - range = range / ARM64_MEMSTART_ALIGN + 1; + range /= ARM64_MEMSTART_ALIGN; memstart_addr -= ARM64_MEMSTART_ALIGN * ((range * memstart_offset_seed) >> 16); }