[PATCH] ocfs2: reset folio to NULL when get folio fails

[Lizhi Xu]

The reproducer uses FAULT_INJECTION to make memory allocation fail, which
causes __filemap_get_folio() to fail, when initializing w_folios[i] in
ocfs2_grab_folios_for_write(), it only returns an error code and the value
of w_folios[i] is the error code, which causes ocfs2_unlock_and_free_folios()
to recycle the invalid w_folios[i] when releasing folios.

Reported-by: syzbot+c2ea94ae47cd7e3881ec@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=c2ea94ae47cd7e3881ec
Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
---
 fs/ocfs2/aops.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 40b6bce12951..89aadc6cdd87 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1071,6 +1071,7 @@ static int ocfs2_grab_folios_for_write(struct address_space *mapping,
 			if (IS_ERR(wc->w_folios[i])) {
 				ret = PTR_ERR(wc->w_folios[i]);
 				mlog_errno(ret);
+				wc->w_folios[i] = NULL;
 				goto out;
 			}
 		}
-- 
2.43.0