afs: Fix updating of i_mode due to 3rd party change

stable inclusion
from stable-5.10.37
commit 95f4e9f33b707787b990017cdfc9ff72cde7f3a5
bugzilla: 51868
CVE: NA

--------------------------------

[ Upstream commit 6e1eb04a ]

Fix afs_apply_status() to mask off the irrelevant bits from status->mode
when OR'ing them into i_mode.  This can happen when a 3rd party chmod
occurs.

Also fix afs_inode_init_from_status() to mask off the mode bits when
initialising i_mode.

Fixes: 260a9803 ("[AFS]: Add "directory write" support.")
Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/afs/inode.c

@@ -102,13 +102,13 @@ static int afs_inode_init_from_status(struct afs_operation *op,
 
 	switch (status->type) {
 	case AFS_FTYPE_FILE:
-		inode->i_mode	= S_IFREG | status->mode;
+		inode->i_mode	= S_IFREG | (status->mode & S_IALLUGO);
 		inode->i_op	= &afs_file_inode_operations;
 		inode->i_fop	= &afs_file_operations;
 		inode->i_mapping->a_ops	= &afs_fs_aops;
 		break;
 	case AFS_FTYPE_DIR:
-		inode->i_mode	= S_IFDIR | status->mode;
+		inode->i_mode	= S_IFDIR |  (status->mode & S_IALLUGO);
 		inode->i_op	= &afs_dir_inode_operations;
 		inode->i_fop	= &afs_dir_file_operations;
 		inode->i_mapping->a_ops	= &afs_dir_aops;
@@ -198,7 +198,7 @@ static void afs_apply_status(struct afs_operation *op,
 	if (status->mode != vnode->status.mode) {
 		mode = inode->i_mode;
 		mode &= ~S_IALLUGO;
-		mode |= status->mode;
+		mode |= status->mode & S_IALLUGO;
 		WRITE_ONCE(inode->i_mode, mode);
 	}