From: Eric Biggers <ebiggers@xxxxxxxxxx>
->setattr() was recently implemented for socket files to sync the socket
inode's uid to the new 'sk_uid' member of struct sock. It does this by
copying over the ia_uid member of struct iattr. However, ia_uid is
actually only valid when ATTR_UID is set in ia_valid, indicating that
the uid is being changed, e.g. by chown. Other metadata operations such
as chmod or utimes leave ia_uid uninitialized. Therefore, sk_uid could
be set to a "garbage" value from the stack.
Fix this by only copying the uid over when ATTR_UID is set.
Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
net/socket.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/socket.c b/net/socket.c
index 8487bf136e5c..a8c2307590b8 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -537,7 +537,7 @@ int sockfs_setattr(struct dentry *dentry, struct iattr *iattr)
{
int err = simple_setattr(dentry, iattr);
- if (!err) {
+ if (!err && (iattr->ia_valid & ATTR_UID)) {
struct socket *sock = SOCKET_I(d_inode(dentry));
sock->sk->sk_uid = iattr->ia_uid;
--
2.11.0
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