linux-stable/fs/ramfs
Kirill A. Shutemov 31b4beb473 ipc/shm: fix crash if CONFIG_SHMEM is not set
Commit c01d5b3007 ("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: c01d5b3007 ("shmem: get_unmapped_area align huge page")
Link: http://lkml.kernel.org/r/20160912102704.140442-1-kirill.shutemov@linux.intel.com
Signed-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>
2016-09-19 15:36:17 -07:00
..
file-mmu.c ipc/shm: fix crash if CONFIG_SHMEM is not set 2016-09-19 15:36:17 -07:00
file-nommu.c tmpfs/ramfs: fix VM_MAYSHARE mappings for NOMMU 2016-05-20 17:58:30 -07:00
inode.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
internal.h fs/ramfs: move ramfs_aops to inode.c 2014-01-23 16:36:58 -08:00
Makefile Remove valueless definition of hard-selected RAMFS option 2007-10-17 08:42:56 -07:00