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authorHyesoo Yu <hyesoo.yu@samsung.com>2023-10-23 11:32:16 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-10-26 02:47:14 +0300
commit76f26535d1446373d4735a252ea4247c39d64ba6 (patch)
tree690e6e660c88d34f6a52be642e71800ee6b5bf16 /mm
parentbe16dd764a69752a31096d1a6b2ad775b728b1bd (diff)
downloadlinux-76f26535d1446373d4735a252ea4247c39d64ba6.tar.xz
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.c6
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++) {