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arm64: mte: Do not allow PROT_MTE on MAP_HUGETLB user mappings

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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: 9f3419315f ("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>
This commit is contained in:
Catalin Marinas
2025-02-20 15:58:01 +00:00
committed by Greg Kroah-Hartman
parent 19b4657de4
commit 93745f5f23
1 changed files with 6 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
arch/arm64/include/asm/mman.h
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@@ -41,9 +41,12 @@ static inline unsigned long arch_calc_vm_flag_bits(struct file *file,
* 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;
}