On Mon, Jun 09, 2025 at 05:12:14AM +0100, Anshuman Khandual wrote:
The arm64 page table dump code can race with concurrent modification of the kernel page tables. When a leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful.
When intermediate levels of table are freed, the dump code will continue to use memory which has been freed and potentially reallocated for another purpose. In such cases, the dump code may dereference bogus addresses, leading to a number of potential problems.
This problem was fixed for ptdump_show() earlier via commit 'bf2b59f60ee1 ("arm64/mm: Hold memory hotplug lock while walking for kernel page table dump")' but a same was missed for ptdump_check_wx() which faced the race condition as well. Let's just take the memory hotplug lock while executing ptdump_check_wx().
Cc: stable@vger.kernel.org Fixes: bbd6ec605c0f ("arm64/mm: Enable memory hot remove") Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Ryan Roberts ryan.roberts@arm.com Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Reported-by: Dev Jain dev.jain@arm.com Signed-off-by: Anshuman Khandual anshuman.khandual@arm.com
Reviewed-by: Catalin Marinas catalin.marinas@arm.com