From: Pedro Tammela <pctammela@mojatatu.com>
Date: Wed, 1 Mar 2023 16:09:47 +0000 (+0100)
Subject: libmount: idmap: fix sock write to child
X-Git-Tag: v2.39-rc1~42
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=567700dfdbcd0a237e274380673a0cb83e78ce06;p=thirdparty%2Futil-linux.git

libmount: idmap: fix sock write to child

The current code writes to sock_fds[0], which is set to -1 on line 227, instead of the correct sock_fds[1].
As a cause, a simple `mount` command which uses idmapping and doesn't specify a user ns hangs indefinitely.
---

diff --git a/libmount/src/hook_idmap.c b/libmount/src/hook_idmap.c
index 7e7c9e742f..9306e5d971 100644
--- a/libmount/src/hook_idmap.c
+++ b/libmount/src/hook_idmap.c
@@ -240,7 +240,7 @@ static int get_userns_fd_from_idmap(struct list_head *idmap)
 	fd_userns = open(path, O_RDONLY | O_CLOEXEC | O_NOCTTY);
 
 	/* Let child know we've persisted its namespace. */
-	(void)write_all(sock_fds[0], &c, 1);
+	(void)write_all(sock_fds[1], &c, 1);
 
 err_wait:
 	rc = wait_for_pid(pid);