From: David Gibson <david@gibson.dropbear.id.au>
Date: Tue, 14 Nov 2006 10:03:38 +0000 (-0800)
Subject: [PATCH] hugetlb: check for brk() entering a hugepage region
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=cb07c9a1864a8eac9f3123e428100d5b2a16e65a;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

[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: David Gibson <david@gibson.dropbear.id.au>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index bdace87d7c01..2526463c99a7 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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);