linux-kernel - [PATCH next] fs: tighten a sanity check in file_attr_to

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Message-ID: <baf7b808-bcf2-4ac1-9313-882c91cc87b2@sabinyo.mountain>
Date: Tue, 15 Jul 2025 18:03:17 -0500
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Andrey Albershteyn <aalbersh@...hat.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Arnd Bergmann <arnd@...db.de>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH next] fs: tighten a sanity check in file_attr_to_fileattr()

The fattr->fa_xflags is a u64 that comes from the user.  This is a sanity
check to ensure that the users are only setting allowed flags.  The
problem is that it doesn't check the upper 32 bits.  It doesn't really
affect anything but for more flexibility in the future, we want to enforce
users zero out those bits.

Fixes: be7efb2d20d6 ("fs: introduce file_getattr and file_setattr syscalls")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 fs/file_attr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file_attr.c b/fs/file_attr.c
index 17745c89e2be..12424d4945d0 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -136,7 +136,7 @@ EXPORT_SYMBOL(copy_fsxattr_to_user);
 static int file_attr_to_fileattr(const struct file_attr *fattr,
 				 struct file_kattr *fa)
 {
-	__u32 mask = FS_XFLAGS_MASK;
+	__u64 mask = FS_XFLAGS_MASK;
 
 	if (fattr->fa_xflags & ~mask)
 		return -EINVAL;
-- 
2.47.2