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[ Upstream commit5330367fa3] After we ALIGN up the address we need to make sure we didn't overflow and resulted in zero address. In that case, we need to make sure that the returned address is greater than mmap_min_addr. This fixes selftest va_128TBswitch --run-hugetlb reporting failures when run as non root user for mmap(-1, MAP_HUGETLB) The bug is that a non-root user requesting address -1 will be given address 0 which will then fail, whereas they should have been given something else that would have succeeded. We also avoid the first mmap(-1, MAP_HUGETLB) returning NULL address as mmap address with this change. So we think this is not a security issue, because it only affects whether we choose an address below mmap_min_addr, not whether we actually allow that address to be mapped. ie. there are existing capability checks to prevent a user mapping below mmap_min_addr and those will still be honoured even without this fix. Fixes:484837601d("powerpc/mm: Add radix support for hugetlb") Reviewed-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.