linux-kernel - [PATCH] cramfs: Verify inode mode when loading from disk

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Message-ID: <ff7dc567-1db3-4939-9b0e-77e91a8d898b@I-love.SAKURA.ne.jp>
Date: Tue, 12 Aug 2025 23:52:37 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: Nicolas Pitre <nico@...xnic.net>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] cramfs: Verify inode mode when loading from disk

The inode mode loaded from corrupted disk can be invalid. Do like what
commit 0a9e74051313 ("isofs: Verify inode mode when loading from disk")
does.

Reported-by: syzbot <syzbot+895c23f6917da440ed0d@...kaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=895c23f6917da440ed0d
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 fs/cramfs/inode.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index b002e9b734f9..12daa85ed941 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -116,9 +116,18 @@ static struct inode *get_cramfs_inode(struct super_block *sb,
 		inode_nohighmem(inode);
 		inode->i_data.a_ops = &cramfs_aops;
 		break;
-	default:
+	case S_IFCHR:
+	case S_IFBLK:
+	case S_IFIFO:
+	case S_IFSOCK:
 		init_special_inode(inode, cramfs_inode->mode,
 				old_decode_dev(cramfs_inode->size));
+		break;
+	default:
+		printk(KERN_DEBUG "CRAMFS: Invalid file type 0%04o for inode %lu.\n",
+		       inode->i_mode, inode->i_ino);
+		iget_failed(inode);
+		return ERR_PTR(-EIO);
 	}
 
 	inode->i_mode = cramfs_inode->mode;
-- 
2.50.1