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authorMiaohe Lin <linmiaohe@huawei.com>2022-06-09 21:08:35 +0800
committerakpm <akpm@linux-foundation.org>2022-06-16 19:48:30 -0700
commited913b055a74b723976f8e885a3395162a0371e6 (patch)
treef072fe1621a6904e3e78a851f9fce5134d365f49 /lib
parent23689037e0986724e3bdc41bb2ee6fa1b497b8f9 (diff)
lib/test_hmm: avoid accessing uninitialized pages
If make_device_exclusive_range() fails or returns pages marked for exclusive access less than required, remaining fields of pages will left uninitialized. So dmirror_atomic_map() will access those yet uninitialized fields of pages. To fix it, do dmirror_atomic_map() iff all pages are marked for exclusive access (we will break if mapped is less than required anyway) so we won't access those uninitialized fields of pages. Link: https://lkml.kernel.org/r/20220609130835.35110-1-linmiaohe@huawei.com Fixes: b659baea7546 ("mm: selftests for exclusive device memory") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_hmm.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index cfe632047839..f2c3015c5c82 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -732,7 +732,7 @@ static int dmirror_exclusive(struct dmirror *dmirror,
mmap_read_lock(mm);
for (addr = start; addr < end; addr = next) {
- unsigned long mapped;
+ unsigned long mapped = 0;
int i;
if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
@@ -741,7 +741,13 @@ static int dmirror_exclusive(struct dmirror *dmirror,
next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
- mapped = dmirror_atomic_map(addr, next, pages, dmirror);
+ /*
+ * Do dmirror_atomic_map() iff all pages are marked for
+ * exclusive access to avoid accessing uninitialized
+ * fields of pages.
+ */
+ if (ret == (next - addr) >> PAGE_SHIFT)
+ mapped = dmirror_atomic_map(addr, next, pages, dmirror);
for (i = 0; i < ret; i++) {
if (pages[i]) {
unlock_page(pages[i]);