From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Wed, 20 Nov 2013 22:16:36 +0000 (+0000)
Subject: Wrong page freed on preallocate_pmds() failure exit
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2a46eed54a28c1e3de701ca4237ce4f8bebf14c6;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

Wrong page freed on preallocate_pmds() failure exit

Note that pmds[i] is simply uninitialized at that point...

Granted, it's very hard to hit (you need split page locks *and*
kmalloc(sizeof(spinlock_t), GFP_KERNEL) failing), but the code is
obviously bogus.

Introduced by commit 09ef4939850a ("x86: add missed
pgtable_pmd_page_ctor/dtor calls for preallocated pmds")

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index a7cccb6d7fec..36aa999b2631 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -209,7 +209,7 @@ static int preallocate_pmds(pmd_t *pmds[])
 		if (!pmd)
 			failed = true;
 		if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
-			free_page((unsigned long)pmds[i]);
+			free_page((unsigned long)pmd);
 			pmd = NULL;
 			failed = true;
 		}