5.15-stable review patch. If anyone has any objections, please let me know.
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From: Catalin Marinas catalin.marinas@arm.com
PROT_MTE (memory tagging extensions) is not supported on all user mmap() types for various reasons (memory attributes, backing storage, CoW handling). The arm64 arch_validate_flags() function checks whether the VM_MTE_ALLOWED flag has been set for a vma during mmap(), usually by arch_calc_vm_flag_bits().
Linux prior to 6.13 does not support PROT_MTE hugetlb mappings. This was added by commit 25c17c4b55de ("hugetlb: arm64: add mte support"). However, earlier kernels inadvertently set VM_MTE_ALLOWED on (MAP_ANONYMOUS | MAP_HUGETLB) mappings by only checking for MAP_ANONYMOUS.
Explicitly check MAP_HUGETLB in arch_calc_vm_flag_bits() and avoid setting VM_MTE_ALLOWED for such mappings.
Fixes: 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()") Cc: stable@vger.kernel.org # 5.10.x-6.12.x Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/mman.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h @@ -31,9 +31,12 @@ static inline unsigned long arch_calc_vm * backed by tags-capable memory. The vm_flags may be overridden by a * filesystem supporting MTE (RAM-based). */ - if (system_supports_mte() && - ((flags & MAP_ANONYMOUS) || shmem_file(file))) - return VM_MTE_ALLOWED; + if (system_supports_mte()) { + if ((flags & MAP_ANONYMOUS) && !(flags & MAP_HUGETLB)) + return VM_MTE_ALLOWED; + if (shmem_file(file)) + return VM_MTE_ALLOWED; + }
return 0; }