The sock counting (sock_update_netprioidx() and sock_update_classid()) was
missing from pidfd's implementation of received fd installation. Replace
the open-coded version with a call to the new receive_fd()
helper.

Thanks to Vamshi K Sthambamkadi [off-list ref] for
catching a missed fput() in an earlier version of this patch.

Fixes: 8649c322f75c ("pid: Implement pidfd_getfd syscall")
Reviewed-by: Sargun Dhillon <redacted>
Signed-off-by: Kees Cook <redacted>
---
 kernel/pid.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/kernel/pid.c b/kernel/pid.c
index f1496b757162..a31c102f4c87 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c

@@ -635,17 +635,8 @@ static int pidfd_getfd(struct pid *pid, int fd)
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
-	ret = security_file_receive(file);
-	if (ret) {
-		fput(file);
-		return ret;
-	}
-
-	ret = get_unused_fd_flags(O_CLOEXEC);
-	if (ret < 0)
-		fput(file);
-	else
-		fd_install(ret, file);
+	ret = receive_fd(file, O_CLOEXEC);
+	fput(file);
 
 	return ret;
 }

-- 
2.25.1