pagevec: Initialise folio_batch->percpu_pvec_drained

Matthew Wilcox (Oracle) · Matthew Wilcox (Oracle) · commit 6840f9094f2b · 2022-01-13T16:50:50.000-05:00
When UBSAN is enabled, it reports an invalid value in __pagevec_release() when accessing pvec->percpu_pvec_drained, which is simply whatever garbage was on the stack. Initialise it when initialising the rest of the folio_batch. Fixes: 1033179 ("pagevec: Add folio_batch") Reported-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
@@ -111,6 +111,7 @@ static_assert(offsetof(struct pagevec, pages) ==
 static inline void folio_batch_init(struct folio_batch *fbatch)
 {
 	fbatch->nr = 0;
+	fbatch->percpu_pvec_drained = false;
 }
 
 static inline unsigned int folio_batch_count(struct folio_batch *fbatch)

Original file line number	Diff line number	Diff line change
`@@ -111,6 +111,7 @@ static_assert(offsetof(struct pagevec, pages) ==`
`111`	`111`	`static inline void folio_batch_init(struct folio_batch *fbatch)`
`112`	`112`	`{`
`113`	`113`	`fbatch->nr = 0;`
	`114`	`+ fbatch->percpu_pvec_drained = false;`
`114`	`115`	`}`
`115`	`116`
`116`	`117`	`static inline unsigned int folio_batch_count(struct folio_batch *fbatch)`