Re: [syzbot] Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link

From: syzbot
Date: Thu Aug 01 2024 - 05:07:14 EST


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Subject: Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link
Author: lizhi.xu@xxxxxxxxxxxxx

if alloc new folio for filemap, init mem to zero

#syz test: upstream 2f8c4f506285

diff --git a/mm/filemap.c b/mm/filemap.c
index 657bcd887fdb..8faa75f6923c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3754,11 +3754,15 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
if (!folio)
return ERR_PTR(-ENOMEM);
err = filemap_add_folio(mapping, folio, index, gfp);
+ printk("err: %d, folio: %p, in: %p, %s\n", err, folio, mapping->host, __func__);
if (unlikely(err)) {
folio_put(folio);
if (err == -EEXIST)
goto repeat;
/* Presumably ENOMEM for xarray node */
+ void *kaddr = kmap_local_folio(folio, 0);
+ memset(kaddr, 0, folio_size(folio));
+ kunmap_local(kaddr);
return ERR_PTR(err);
}