diff options
| author | Hyesoo Yu | 2023-10-23 17:32:16 +0900 |
|---|---|---|
| committer | Andrew Morton | 2023-10-25 16:47:14 -0700 |
| commit | 76f26535d1446373d4735a252ea4247c39d64ba6 (patch) | |
| tree | 690e6e660c88d34f6a52be642e71800ee6b5bf16 /mm | |
| parent | be16dd764a69752a31096d1a6b2ad775b728b1bd (diff) | |
mm: page_alloc: check the order of compound page even when the order is zero
For compound pages, the head sets the PG_head flag and the tail sets the
compound_head to indicate the head page. If a user allocates a compound
page and frees it with a different order, the compound page information
will not be properly initialized. To detect this problem,
compound_order(page) and the order argument are compared, but this is not
checked when the order argument is zero. That error should be checked
regardless of the order.
Link: https://lkml.kernel.org/r/20231023083217.1866451-1-hyesoo.yu@samsung.com
Signed-off-by: Hyesoo Yu <hyesoo.yu@samsung.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_alloc.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index aa90758950a7..5f46c7f85cb1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1079,6 +1079,7 @@ static __always_inline bool free_pages_prepare(struct page *page, int bad = 0; bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags); bool init = want_init_on_free(); + bool compound = PageCompound(page); VM_BUG_ON_PAGE(PageTail(page), page); @@ -1097,16 +1098,15 @@ static __always_inline bool free_pages_prepare(struct page *page, return false; } + VM_BUG_ON_PAGE(compound && compound_order(page) != order, page); + /* * Check tail pages before head page information is cleared to * avoid checking PageCompound for order-0 pages. */ if (unlikely(order)) { - bool compound = PageCompound(page); int i; - VM_BUG_ON_PAGE(compound && compound_order(page) != order, page); - if (compound) page[1].flags &= ~PAGE_FLAGS_SECOND; for (i = 1; i < (1 << order); i++) { |