[PATCH stable 5.10.y-6.12.y] arm64: mte: Do not allow PROT_MTE on MAP_HUGETLB user mappings
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 ---
Hi Greg,
This patch applies cleanly on top of the stable-rc/linux-6.12.y to 5.10.y LTS, so I'm only sending it once. It's not for 6.13 onwards since those kernels support hugetlbfs with MTE.
Thanks,
Catalin
arch/arm64/include/asm/mman.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h index 798d965760d4..5a280ac7570c 100644 --- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h @@ -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; }
On Thu, Feb 20, 2025 at 03:58:01PM +0000, Catalin Marinas wrote:
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
Hi Greg,
This patch applies cleanly on top of the stable-rc/linux-6.12.y to 5.10.y LTS, so I'm only sending it once. It's not for 6.13 onwards since those kernels support hugetlbfs with MTE.
Thanks for this, I'll queue it up after the next round of releases.
greg k-h
[ Sasha's backport helper bot ]
Hi,
Summary of potential issues: ⚠️ Could not find matching upstream commit
No upstream commit was identified. Using temporary commit for testing.
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.12.y | Success | Success | | stable/linux-5.10.y | Success | Success |
On Thu, Feb 20, 2025 at 03:58:01PM +0000, Catalin Marinas wrote:
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
Hi Greg,
This patch applies cleanly on top of the stable-rc/linux-6.12.y to 5.10.y LTS, so I'm only sending it once. It's not for 6.13 onwards since those kernels support hugetlbfs with MTE.
Now queued up,t hanks.
greg k-h
On Fri, Feb 21, 2025 at 04:17:09PM +0100, Greg Kroah-Hartman wrote:
On Thu, Feb 20, 2025 at 03:58:01PM +0000, Catalin Marinas wrote:
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
Hi Greg,
This patch applies cleanly on top of the stable-rc/linux-6.12.y to 5.10.y LTS, so I'm only sending it once. It's not for 6.13 onwards since those kernels support hugetlbfs with MTE.
Now queued up, thanks.
Thanks Greg.
linux-stable-mirror@lists.linaro.org
-
Catalin Marinas -
Greg Kroah-Hartman -
Sasha Levin