6.12-stable review patch. If anyone has any objections, please let me know.
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From: Ryan Roberts ryan.roberts@arm.com
commit 2b1283e1ea9b5e0b06f075f79391a51d9f70749b upstream.
When the range of present physical memory is sufficiently small enough and the reserved address space for the linear map is sufficiently large enough, The linear map base address is randomized in arm64_memblock_init().
Prior to commit 62cffa496aac ("arm64/mm: Override PARange for !LPA2 and use it consistently"), we decided if the sizes were suitable with the help of the raw mmfr0.parange. But the commit changed this to use the sanitized version instead. But the function runs before the register has been sanitized so this returns 0, interpreted as a parange of 32 bits. Some fun wrapping occurs and the logic concludes that there is enough room to randomize the linear map base address, when really there isn't. So the top of the linear map ends up outside the reserved address space.
Since the PA range cannot be overridden in the first place, restore the mmfr0 reading logic to its state prior to 62cffa496aac, where the raw register value is used.
Reported-by: Luiz Capitulino luizcap@redhat.com Suggested-by: Ard Biesheuvel ardb@kernel.org Closes: https://lore.kernel.org/all/a3d9acbe-07c2-43b6-9ba9-a7585f770e83@redhat.com/ Fixes: 62cffa496aac ("arm64/mm: Override PARange for !LPA2 and use it consistently") Signed-off-by: Ryan Roberts ryan.roberts@arm.com Link: https://lore.kernel.org/r/20250225114638.2038006-1-ryan.roberts@arm.com Cc: stable@vger.kernel.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/mm/init.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
--- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -278,12 +278,7 @@ void __init arm64_memblock_init(void)
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { extern u16 memstart_offset_seed; - - /* - * Use the sanitised version of id_aa64mmfr0_el1 so that linear - * map randomization can be enabled by shrinking the IPA space. - */ - u64 mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1); + u64 mmfr0 = read_cpuid(ID_AA64MMFR0_EL1); int parange = cpuid_feature_extract_unsigned_field( mmfr0, ID_AA64MMFR0_EL1_PARANGE_SHIFT); s64 range = linear_region_size -