The patch titled
Subject: /proc/kpageflags: prevent an integer overflow in stable_page_flags()
has been added to the -mm tree. Its filename is
proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Toshiki Fukasawa <t-fukasawa@xxxxxxxxxxxxx>
Subject: /proc/kpageflags: prevent an integer overflow in stable_page_flags()
stable_page_flags() returns kpageflags info in u64, but it uses "1 <<
KPF_*" internally which is considered as int. This type mismatch causes
no visible problem now, but it will if you set bit 32 or more as done in a
subsequent patch. So use BIT_ULL in order to avoid future overflow
issues.
Link: http://lkml.kernel.org/r/20190725023100.31141-2-t-fukasawa@xxxxxxxxxxxxx
Signed-off-by: Toshiki Fukasawa <t-fukasawa@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Junichi Nomura <j-nomura@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/page.c | 37 ++++++++++++++++++-------------------
1 file changed, 18 insertions(+), 19 deletions(-)
--- a/fs/proc/page.c~proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags
+++ a/fs/proc/page.c
@@ -95,7 +95,7 @@ u64 stable_page_flags(struct page *page)
* it differentiates a memory hole from a page with no flags
*/
if (!page)
- return 1 << KPF_NOPAGE;
+ return BIT_ULL(KPF_NOPAGE);
k = page->flags;
u = 0;
@@ -107,22 +107,22 @@ u64 stable_page_flags(struct page *page)
* simple test in page_mapped() is not enough.
*/
if (!PageSlab(page) && page_mapped(page))
- u |= 1 << KPF_MMAP;
+ u |= BIT_ULL(KPF_MMAP);
if (PageAnon(page))
- u |= 1 << KPF_ANON;
+ u |= BIT_ULL(KPF_ANON);
if (PageKsm(page))
- u |= 1 << KPF_KSM;
+ u |= BIT_ULL(KPF_KSM);
/*
* compound pages: export both head/tail info
* they together define a compound page's start/end pos and order
*/
if (PageHead(page))
- u |= 1 << KPF_COMPOUND_HEAD;
+ u |= BIT_ULL(KPF_COMPOUND_HEAD);
if (PageTail(page))
- u |= 1 << KPF_COMPOUND_TAIL;
+ u |= BIT_ULL(KPF_COMPOUND_TAIL);
if (PageHuge(page))
- u |= 1 << KPF_HUGE;
+ u |= BIT_ULL(KPF_HUGE);
/*
* PageTransCompound can be true for non-huge compound pages (slab
* pages or pages allocated by drivers with __GFP_COMP) because it
@@ -133,14 +133,13 @@ u64 stable_page_flags(struct page *page)
struct page *head = compound_head(page);
if (PageLRU(head) || PageAnon(head))
- u |= 1 << KPF_THP;
+ u |= BIT_ULL(KPF_THP);
else if (is_huge_zero_page(head)) {
- u |= 1 << KPF_ZERO_PAGE;
- u |= 1 << KPF_THP;
+ u |= BIT_ULL(KPF_ZERO_PAGE);
+ u |= BIT_ULL(KPF_THP);
}
} else if (is_zero_pfn(page_to_pfn(page)))
- u |= 1 << KPF_ZERO_PAGE;
-
+ u |= BIT_ULL(KPF_ZERO_PAGE);
/*
* Caveats on high order pages: page->_refcount will only be set
@@ -148,23 +147,23 @@ u64 stable_page_flags(struct page *page)
* SLOB won't set PG_slab at all on compound pages.
*/
if (PageBuddy(page))
- u |= 1 << KPF_BUDDY;
+ u |= BIT_ULL(KPF_BUDDY);
else if (page_count(page) == 0 && is_free_buddy_page(page))
- u |= 1 << KPF_BUDDY;
+ u |= BIT_ULL(KPF_BUDDY);
if (PageOffline(page))
- u |= 1 << KPF_OFFLINE;
+ u |= BIT_ULL(KPF_OFFLINE);
if (PageTable(page))
- u |= 1 << KPF_PGTABLE;
+ u |= BIT_ULL(KPF_PGTABLE);
if (page_is_idle(page))
- u |= 1 << KPF_IDLE;
+ u |= BIT_ULL(KPF_IDLE);
u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
if (PageTail(page) && PageSlab(compound_head(page)))
- u |= 1 << KPF_SLAB;
+ u |= BIT_ULL(KPF_SLAB);
u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
@@ -177,7 +176,7 @@ u64 stable_page_flags(struct page *page)
u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
if (PageSwapCache(page))
- u |= 1 << KPF_SWAPCACHE;
+ u |= BIT_ULL(KPF_SWAPCACHE);
u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
_
Patches currently in -mm which might be from t-fukasawa@xxxxxxxxxxxxx are
proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags.patch
proc-kpageflags-do-not-use-uninitialized-struct-pages.patch
