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lib/test_hmm: avoid accessing uninitialized pages
[ Upstream commited913b055a
] 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:b659baea75
("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> Signed-off-by: Sasha Levin <sashal@kernel.org>
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1 changed files with 8 additions and 2 deletions
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@ -731,7 +731,7 @@ static int dmirror_exclusive(struct dmirror *dmirror,
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mmap_read_lock(mm);
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for (addr = start; addr < end; addr = next) {
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unsigned long mapped;
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unsigned long mapped = 0;
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int i;
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if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
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@ -740,7 +740,13 @@ static int dmirror_exclusive(struct dmirror *dmirror,
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next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
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ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
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mapped = dmirror_atomic_map(addr, next, pages, dmirror);
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/*
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* Do dmirror_atomic_map() iff all pages are marked for
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* exclusive access to avoid accessing uninitialized
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* fields of pages.
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*/
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if (ret == (next - addr) >> PAGE_SHIFT)
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mapped = dmirror_atomic_map(addr, next, pages, dmirror);
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for (i = 0; i < ret; i++) {
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if (pages[i]) {
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unlock_page(pages[i]);
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