[BUG mm-unstable] BUG: KASAN: use-after-free in shrink_folio_list+0x9f4/0x1ae0
Matthew Wilcox
willy at infradead.org
Fri Jul 7 11:33:15 PDT 2023
On Fri, Jul 07, 2023 at 02:12:06PM -0400, David Wysochanski wrote:
> I think myself / Daire Byrne may have already tracked this down and I
> found a 1-liner that fixed a similar crash in his environment.
>
> Can you try this patch on top and let me know if it still crashes?
> https://github.com/DaveWysochanskiRH/kernel/commit/902c990e311120179fa5de99d68364b2947b79ec
Said one-liner:
- struct address_space *mapping = folio->mapping;
+ struct address_space *mapping = folio_mapping(folio);
This will definitely fix the problem. shrink_folio_list() sees
anonymous folios as well as file folios.
I wonder if we want to go a step further and introduce ...
+static inline bool __folio_needs_release(struct address_space *mapping,
+ struct folio *folio)
+{
+ return folio_has_private(folio) ||
+ (mapping && mapping_release_always(mapping));
+}
+
/*
* Return true if a folio needs ->release_folio() calling upon it.
*/
static inline bool folio_needs_release(struct folio *folio)
{
- struct address_space *mapping = folio->mapping;
-
- return folio_has_private(folio) ||
- (mapping && mapping_release_always(mapping));
+ return __folio_needs_release(folio_mapping(folio), folio);
}
since two of the three callers already have done the necessary dance to
get the mapping (and they're the two which happen regularly; the third
is an unusual situation).
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