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Kirill A. Shutemov authored
Commit c01d5b30 ("shmem: get_unmapped_area align huge page") makes use of shm_get_unmapped_area() in shm_file_operations() unconditional to CONFIG_MMU. As Tony Battersby pointed this can lead NULL-pointer dereference on machine with CONFIG_MMU=y and CONFIG_SHMEM=n. In this case ipc/shm is backed by ramfs which doesn't provide f_op->get_unmapped_area for configurations with MMU. The solution is to provide dummy f_op->get_unmapped_area for ramfs when CONFIG_MMU=y, which just call current->mm->get_unmapped_area(). Fixes: c01d5b30 ("shmem: get_unmapped_area align huge page") Link: http://lkml.kernel.org/r/20160912102704.140442-1-kirill.shutemov@linux.intel.comSigned-off-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by:
Tony Battersby <tonyb@cybernetics.com> Tested-by:
Tony Battersby <tonyb@cybernetics.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.7.x] Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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