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Commit cb07c9a1 authored by David Gibson's avatar David Gibson Committed by Linus Torvalds
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[PATCH] hugetlb: check for brk() entering a hugepage region 



Unlike mmap(), the codepath for brk() creates a vma without first checking
that it doesn't touch a region exclusively reserved for hugepages.  On
powerpc, this can allow it to create a normal page vma in a hugepage
region, causing oopses and other badness.

Add a test to prevent this.  With this patch, brk() will simply fail if it
attempts to move the break into a hugepage reserved region.

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 68589bc3

mm/mmap.c

+4 −0
Original line number Diff line number Diff line
@@ -1880,6 +1880,10 @@ unsigned long do_brk(unsigned long addr, unsigned long len) 
	if ((addr + len) > TASK_SIZE || (addr + len) < addr)

		return -EINVAL;



	error = is_hugepage_only_range(current->mm, addr, len);

	if (error)

		return error;



	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;



	error = arch_mmap_check(addr, len, flags);