From 1b0b9cc8d3793e31b313e6c9685513b08cd883c4 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 12 Jun 2019 11:43:13 -0700 Subject: [PATCH] vfs: fsmount: add missing mntget() sys_fsmount() needs to take a reference to the new mount when adding it to the anonymous mount namespace. Otherwise the filesystem can be unmounted while it's still in use, as found by syzkaller. Reported-by: Mark Rutland Reported-by: syzbot+99de05d099a170867f22@syzkaller.appspotmail.com Reported-by: syzbot+7008b8b8ba7df475fdc8@syzkaller.appspotmail.com Fixes: 93766fbd2696 ("vfs: syscall: Add fsmount() to create a mount for a superblock") Signed-off-by: Eric Biggers Signed-off-by: Al Viro --- fs/namespace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/namespace.c b/fs/namespace.c index b26778bdc236e..5dc137a22d406 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3445,6 +3445,7 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, ns->root = mnt; ns->mounts = 1; list_add(&mnt->mnt_list, &ns->list); + mntget(newmount.mnt); /* Attach to an apparent O_PATH fd with a note that we need to unmount * it, not just simply put it. -- 2.39.2