From a66477b0efe511d98dde3e4aaeb189790e6f0a39 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Tue, 2 Apr 2019 09:26:52 +0200
Subject: [PATCH] drm/ttm: fix out-of-bounds read in ttm_put_pages() v2
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Git-commit: a66477b0efe511d98dde3e4aaeb189790e6f0a39
Patch-mainline: v5.1-rc6
References: CVE-2019-19927 bsc#1160147 bsc#1111666
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 <jannh@google.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: 5c42c64f7d54 ("drm/ttm: fix the fix for huge compound pages")
Cc: stable@vger.kernel.org
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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;
--
2.16.4