When ttm_put_pages() tries to figure out whether it's dealing with
transparent hugepages, it just reads past the bounds of the pages array
without a check.

v2: simplify the test if enough pages are left in the array (Christian).

Signed-off-by: Jann Horn <ja...@google.com>
Signed-off-by: Christian König <christian.koe...@amd.com>
Fixes: 5c42c64f7d54 ("drm/ttm: fix the fix for huge compound pages")
Cc: sta...@vger.kernel.org
---
 drivers/gpu/drm/ttm/ttm_page_alloc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c 
b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index f841accc2c00..f77c81db161b 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -730,7 +730,8 @@ static void ttm_put_pages(struct page **pages, unsigned 
npages, int flags,
                        }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-                       if (!(flags & TTM_PAGE_FLAG_DMA32)) {
+                       if (!(flags & TTM_PAGE_FLAG_DMA32) &&
+                           (npages - i) >= HPAGE_PMD_NR) {
                                for (j = 0; j < HPAGE_PMD_NR; ++j)
                                        if (p++ != pages[i + j])
                                            break;
@@ -759,7 +760,7 @@ static void ttm_put_pages(struct page **pages, unsigned 
npages, int flags,
                unsigned max_size, n2free;
 
                spin_lock_irqsave(&huge->lock, irq_flags);
-               while (i < npages) {
+               while ((npages - i) >= HPAGE_PMD_NR) {
                        struct page *p = pages[i];
                        unsigned j;
 
-- 
2.17.1

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