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

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@xxxxxxxxxxxxxxx.

***

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

why folio not inited?

#syz test: upstream 2f8c4f506285

diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c
index 6ef735bd841a..7cffc1059c42 100644
--- a/fs/squashfs/symlink.c
+++ b/fs/squashfs/symlink.c
@@ -49,6 +49,11 @@ static int squashfs_symlink_read_folio(struct file *file, struct folio *folio)
 	/*
 	 * Skip index bytes into symlink metadata.
 	 */
+	if (length < 0) {
+		error = -EINVAL;
+		goto out;
+	}
+
 	if (index) {
 		bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
 								index);
}